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Versions: 00 01 02 03 04 rfc2070                                Historic
Network Working Group                                       F. Yergeau
Internet Draft                                                G. Nicol
<draft-ietf-html-i18n-04.txt>                                 G. Adams
Expires 2 December 1996                                      M. Duerst
                                                           27 May 1996

         Internationalization of the Hypertext Markup Language

Status of this Memo

   This document is an Internet-Draft.  Internet-Drafts are working doc-
   uments of the Internet Engineering Task Force (IETF), its areas, and
   its working groups. Note that other groups may also distribute work-
   ing documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
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   Distribution of this document is unlimited.  Please send comments to
   the HTML working group (HTML-WG) of the Internet Engineering Task
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   The Hypertext Markup Language (HTML) is a simple markup language used
   to create hypertext documents that are platform independent.  Ini-
   tially, the application of HTML on the World Wide Web was seriously
   restricted by its reliance on the ISO-8859-1 coded character set,
   which is appropriate only for Western European languages.  Despite
   this restriction, HTML has been widely used with other languages,
   using other coded character sets or character encodings, at the
   expense of interoperability.

   This document is meant to address the issue of the

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   internationalization (i18n, i followed by 18 letters followed by n)
   of HTML by extending the specification of HTML and giving additional
   recommendations for proper internationalization support.  A foremost
   consideration is to make sure that HTML remains a valid application
   of SGML, while enabling its use in all languages of the world.

Table of contents

   1.  Introduction .................................................. 2
     1.1. Scope ...................................................... 3
     1.2. Conformance ................................................ 3
   2. The document character set ..................................... 4
     2.1. Reference processing model ................................. 4
     2.2. The document character set ................................. 6
     2.3. Undisplayable characters ................................... 8
   3. The LANG attribute.............................................. 8
   4. Additional entities, attributes and elements ................... 9
     4.1. Full Latin-1 entity set .................................... 9
     4.2. Markup for language-dependent presentation ................. 9
   5. Forms ..........................................................15
     5.1. DTD additions ..............................................15
     5.2. Form submission ............................................15
   6. Miscellaneous ..................................................17
   7. HTML public text ...............................................18
     7.1. HTML DTD ...................................................18
     7.2. SGML declaration for HTML ..................................34
     7.3. ISO Latin 1 character entity set ...........................35
   Bibliography ......................................................38
   Authors' Addresses ................................................40

1.  Introduction

   The Hypertext Markup Language (HTML) is a simple markup language used
   to create hypertext documents that are platform independent.  Ini-
   tially, the application of HTML on the World Wide Web was seriously
   restricted by its reliance on the ISO-8859-1 coded character set,
   which is appropriate only for Western European languages.  Despite
   this restriction, HTML has been widely used with other languages,
   using other coded character sets or character encodings, through var-
   ious ad hoc extensions to the language [TAKADA].

   This document is meant to address the issue of the internationaliza-
   tion of HTML by extending the specification of HTML and giving addi-
   tional recommendations for proper internationalization support.  It
   is in good part based on a paper by one of the authors on multilin-
   gualism on the WWW [NICOL].  A foremost consideration is to make sure

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   that HTML remains a valid application of SGML, while enabling its use
   in all languages of the world.

   The specific issues addressed are the SGML document character set to
   be used for HTML, the proper treatment of the charset parameter asso-
   ciated with the "text/html" content type and the specification of
   some additional elements and entities.

1.1 Scope

   HTML has been in use by the World-Wide Web (WWW) global information
   initiative since 1990.  This specification extends the capabilities
   of HTML 2.0 (RFC 1866), primarily by removing the restriction to the
   ISO-8859-1 coded character set [ISO-8859-1].

   HTML is an application of ISO Standard 8879:1986, Information Pro-
   cessing Text and Office Systems -- Standard Generalized Markup Lan-
   guage (SGML) [ISO-8879]. The HTML Document Type Definition (DTD) is a
   formal definition of the HTML syntax in terms of SGML.  This specifi-
   cation amends the DTD of HTML in order to make it applicable to docu-
   ments encompassing a character repertoire much larger than that of
   ISO-8859-1, while still remaining SGML conformant.

   Both formal and actual development of HTML are advancing very fast.
   The features described in this document are designed so that they can
   (and should) be added to other forms of HTML besides that described
   in RFC 1866. Where indicated, attributes introduced here should be
   extended to the appropriate elements.

1.2 Conformance

   This specification changes slightly the conformance requirements of
   HTML documents and HTML user agents.

1.2.1 Documents

   All HTML 2.0 conforming documents remain conforming with this speci-
   fication.  However, the extensions introduced here make valid cer-
   tains documents that would not be HTML 2.0 conforming, in particular
   those containing characters or character references outside of the
   repertoire of ISO 8859-1, and those containing markup introduced

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1.2.2. User agents

   In addition to the requirements of RFC 1866, the following require-
   ments are placed on HTML user agents.

      To ensure interoperability and proper support for at least
      ISO-8859-1 in an environment where character encoding schemes
      other than ISO-8859-1 are present, user agents must correctly
      interpret the charset parameter accompanying an HTML document
      received from the network.

      Furthermore, conforming user-agents are required to at least parse
      correctly all numeric character references within the range of ISO
      10646-1 [ISO-10646].

      Conforming user-agents are required to apply the BIDI presentation
      algorithm if they display right-to-left characters.  If there is
      no displayable right-to-left character in a document, there is no
      need to apply BIDI processing.

2. The document character set

2.1. Reference processing model

   This overview explains a reference processing model used for HTML,
   and in particular the SGML concept of a document character set. An
   actual implementation may widely differ in its internal workings from
   the model given below, but should behave as described to an outside

   Because there are various widely differing encodings of text, SGML
   does not directly address the question of how characters are encoded
   e.g. in a file. SGML views the characters as a single set (called a
   "character repertoire"), and a "code set" that assigns an integer
   number (known as "character number") to each character in the reper-
   toire.  The document character set declaration defines what each of
   the character numbers represents [GOLD90, p. 451].  In most cases, an
   SGML DTD and all documents that refer to it have a single document
   character set, and all markup and data characters are part of this

   HTML, as an application of SGML, does not directly address the ques-
   tion of how characters are encoded as octets in external representa-
   tions such as files. This is deferred to mechanisms external to HTML,
   such as MIME as used by the HTTP protocol or by electronic mail.

   For the HTTP protocol [RFC1945], the way characters are encoded is

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   defined by the "charset" parameter[1] of the "Content-Type" field of
   the header of an HTTP response. For example, to indicate that the
   transmitted document is encoded in the "JIS" encoding of Japanese
   [RFC1468], the header will contain the following line:

   Content-Type: text/html; charset=ISO-2022-JP

   The HTTP protocol also defines a mechanism for the client to specify
   the character encodings it can accept. Clients and servers are
   strongly requested to use these mechanisms to assure correct trans-
   mission and interpretation of any document. Provisions that can be
   taken to help correct interpretation, even in cases where a server or
   client do not yet use these mechanisms, are described in section 6.

   Similarly, if HTML documents are transferred by electronic mail, the
   character encoding is defined by the "charset" parameter of the "Con-
   tent-Type" MIME header line [RFC1521], and defaults to US-ASCII in
   its absence.

   In the case any other way of transferring and storing HTML documents
   are defined or become popular, it is advised that similar provisions
   be made to clearly identify the character encoding used and/or to use
   a single/default encoding capable of representing the widest range of
   characters used in an international context.

   Whatever the external character encoding may be, the reference pro-
   cessing model translates it to a representation of the document char-
   acter set specified in Section 2.2 before processing specific to
   SGML/HTML.  The reference processing model can be depicted as fol-

     [resource]->[decoder]->[entity ]->[ SGML ]->[application]->[display]
                            [manager]  [parser]
                                ^          |
                                |          |

   The decoder is responsible for decoding the external representation
   of the resource to a representation using the document character set.
   The entity manager, the parser, and the application deal only with
   characters of the document character set.  A display-oriented part of
   the application or the display machinery itself may again convert
  1 The term "charset" in MIME is used to designate a char-
acter encoding, rather than a coded character set as the
term may suggest.  A character encoding is a mapping (possi-
bly many-to-one) of a sequence of octets to a sequence of
characters taken from one or more character repertoires.

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   characters represented in the document character set to some other
   representation more suitable for their purpose. In any case, the
   entity manager, the parser, and the application, as far as character
   semantics are concerned, are using the HTML document character set

   An actual implementation may choose, or not, to translate the docu-
   ment into some encoding of the document character set as described
   above; the behaviour described by this reference processing model can
   be achieved otherwise.  This subject is well out of the scope of this
   specification, however, and the reader is invited to consult the SGML
   standard [ISO-8879] or an SGML handbook [BRYAN88] [GOLD90] [VANH90]
   [SQ91] for further information.

   The most important consequence of this reference processing model is
   that numeric character references are always resolved with respect to
   the fixed document character set, and thus to the same characters,
   whatever the external encoding actually used. For an example, see
   Section 2.2.

2.2. The document character set

   The document character set, in the SGML sense, is the Universal Char-
   acter Set (UCS) of ISO 10646:1993 [ISO-10646], as amended.  Cur-
   rently, this is code-by-code identical with the Unicode standard,
   version 1.1 [UNICODE].

        NOTE -- implementers should be aware that ISO 10646 is
        amended from time to time; 4 amendments have been adopted
        since the initial 1993 publication, none of which signifi-
        cantly affects this specification.  A fifth amendment, now
        under consideration, will introduce incompatible changes to
        the standard: 6556 Korean Hangul syllables allocated
        between code positions 3400 and 4DFF (hexadecimal) will be
        moved to new positions (and 4516 new syllables added), thus
        making references to the old positions invalid.  Since the
        Unicode consortium has already adopted a corresponding
        amendment for inclusion in the forthcoming Unicode 2.0,
        adoption of DAM 5 is considered likely and implementers
        should probably consider the old code positions as already
        invalid.  Despite this one-time change, the relevant stan-
        dard bodies appear to remain committed not to change any
        allocated code position in the future.  To encode Korean
        Hangul irrespective of these changes, the combining Hangul
        Jamo in the range 1110-11F9 can be used.

   The adoption of this document character set implies a change in the
   SGML declaration specified in the HTML 2.0 specification (section 9.5

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   of [RFC1866]).  The change amounts to removing the first BASESET
   specification and its accompanying DESCSET declaration, replacing
   them with the following declaration:

     BASESET "ISO Registration Number 177//CHARSET
              ISO/IEC 10646-1:1993 UCS-4 with implementation level 3
              //ESC 2/5 2/15 4/6"
     DESCSET  0   9     UNUSED
              9   2     9
              11  2     UNUSED
              13  1     13
              14  18    UNUSED
              32  95    32
              127 1     UNUSED
              128 32    UNUSED
              160 2147483486 160

   Making the UCS the document character set does not create non-
   conformance of any expression, construct or document that is conform-
   ing to HTML 2.0.  It does make conforming certain constructs that are
   not admissible in HTML 2.0.  One consequence is that data characters
   outside the repertoire of ISO-8859-1, but within that of UCS-4 become
   valid SGML characters.  Another is that the upper limit of the range
   of numeric character references is extended from 255 to 2147483645;
   thus, &#1048; is a valid reference to a "CYRILLIC CAPITAL LETTER I".
   [ERCS] is a good source of information on Unicode and SGML, although
   its scope and technical content differ greatly from this specifica-

        NOTE -- the above SGML declaration, like that of HTML 2.0,
        specifies the character numbers 128 to 159 (80 to 9F hex)
        as UNUSED.  This means that numeric character references
        within that range (e.g.  &#146;) are illegal in HTML.  Nei-
        ther ISO 8859-1 nor ISO 10646 contain characters in that
        range, which is reserved for control characters.

   ISO 10646-1:1993 is the most encompassing character set currently
   existing, and there is no other character set that could take its
   place as the document character set for HTML. If nevertheless for a
   specific application there is a need to use characters outside this
   standard, this should be done by avoiding any conflicts with present
   or future versions of ISO 10646, i.e. by assigning these characters
   to a private zone. Also, it should be borne in mind that such a use
   will be highly unportable; in many cases, it may be better to use
   inline bitmaps.

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2.3. Undisplayable characters

   With the document character set being the full ISO 10646, the possi-
   bility that a character cannot be displayed due to lack of appropri-
   ate resources (fonts) cannot be avoided. Because there are many dif-
   ferent things that can be done in such a case, this document does not
   prescribe any specific behaviour. Depending on the implementation,
   this may also be handled by the underlaying display system and not
   the application itself.  The following considerations, however, may
   be of help:

   -  A clearly visible, but unobtrusive behaviour should be preferred.
      Some documents may contain many characters that cannot be renden-
      dered, and so showing an alert for each of them is not the right
      thing to do.

   -  In case a numeric representation of the missing character is
      given, its hexadecimal (not decimal) form is to be preferred,
      because this form is used in character set standards [ERCS].

3. The LANG attribute

   Language tags can be used to control rendering of a marked up docu-
   ment in various ways: glyph disambiguation, in cases where the char-
   acter encoding is not sufficient to resolve to a specific glyph; quo-
   tation marks; hyphenation; ligatures; spacing; voice synthesis; etc.
   Independently of rendering issues, language markup is useful as con-
   tent markup for purposes such as classification and searching.

   Since any text can logically be assigned a language, almost all HTML
   elements admit the LANG attribute.  The DTD reflects this.  It is
   also intended that any new element introduced in later versions of
   HTML will admit the LANG attribute, unless there is a good reason not
   to do so.

   The language attribute, LANG, takes as its value a language tag that
   identifies a natural language spoken, written, or otherwise conveyed
   by human beings for communication of information to other human
   beings. Computer languages are explicitly excluded.

   The syntax and registry of HTML language tags is the same as that
   defined by RFC 1766 [RFC1766]. In summary, a language tag is composed
   of one or more parts: A primary language tag and a possibly empty
   series of subtags:

        language-tag  = primary-tag *( "-" subtag )
        primary-tag   = 1*8ALPHA
        subtag        = 1*8ALPHA

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   Whitespace is not allowed within the tag and all tags are case-
   insensitive. The namespace of language tags is administered by the
   IANA. Example tags include:

       en, en-US, en-cockney, i-cherokee, x-pig-latin

   In the context of HTML, a language tag is not to be interpreted as a
   single token, as per RFC 1766, but as a hierarchy. For example, a
   user agent that adjusts rendering according to language should con-
   sider that it has a match when a language tag in a style sheet entry
   matches the initial portion of the language tag of an element. An
   exact match should be preferred. This interpretation allows an ele-
   ment marked up as, for instance, "en-US" to trigger styles corre-
   sponding to, in order of preference, US-English ("en-US") or 'plain'
   or 'international' English ("en").

        NOTE -- using the language tag as a hierarchy does not
        imply that all languages with a common prefix will be
        understood by those fluent in one or more of those lan-
        guages; it simply allows the user to request this commonal-
        ity when it is true for that user.

   The rendering of elements may be affected by the LANG attribute.  For
   any element, the value of the LANG attribute overrides the value
   specified by the LANG attribute of any enclosing element and the
   value (if any) of the HTTP Content-Language header. If none of these
   are set, a suitable default, perhaps controlled by user preferences,
   by automatic context analysis or by the user's locale, should be used
   to control rendering.

4. Additional entities, attributes and elements

4.1. Full Latin-1 entity set

   According to the suggestion of section 14 of [RFC1866], the set of
   Latin-1 entities is extended to cover the whole right part of
   ISO-8859-1 (all code positions with the high-order bit set), includ-
   ing the already commonly used &nbsp;, &copy; and &reg;.  The names of
   the entities are taken from the appendices of SGML [ISO-8879].  A
   list is provided in section 7.3 of this specification.

4.2. Markup for language-dependent presentation

4.2.1. Overview

   For the correct presentation of text in certain languages (irrespec-
   tive of formatting issues), some support in the form of additional

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   entities and elements is needed.

   In particular, the following features are dealt with:

   -  Markup of bidirectional text, i.e. text where left-to-right and
      right-to-left scripts are mixed.

   -  Control of cursive joining behaviour in contexts where the default
      behaviour is not appropriate.

   -  Language-dependent rendering of short (in-line) quotations.

   -  Better justification control for languages where this is impor-

   -  Superscripts and subscripts for languages where they appear as
      part of general text.

   Some of the above features need very little additional support; oth-
   ers need more. The additional features are introduced below with
   brief comments only. Explanations on cursive joining behaviour and
   bidirectional text follow later.  For cursive joining behaviour and
   bidirectional text, this document follows [UNICODE] in that: i) char-
   acter semantics, where applicable, are identical to [UNICODE], and
   ii) where functionality is moved to HTML as a higher level protocol,
   this is done in a way that allows straightforward conversion to the
   lower-level mechanisms defined in [UNICODE].

4.2.2. List of entities, elements, and attributes

   First, a generic container is needed to carry the LANG and DIR (see
   below) attributes in cases where no other element is appropriate; the
   SPAN element is introduced for that purpose.

   A set of named character entities is added for use with bidirectional
   rendering and cursive joining control:

   <!ENTITY zwnj CDATA "&#8204;"--=zero width non-joiner-->
   <!ENTITY zwj  CDATA "&#8205;"--=zero width joiner-->
   <!ENTITY lrm  CDATA "&#8206;"--=left-to-right mark-->
   <!ENTITY rlm  CDATA "&#8207;"--=right-to-left mark-->

   These entities can be used in place of the corresponding formatting
   characters whenever convenient, for example to ease keyboard entry or
   when a formatting character is not available in the character encod-
   ing of the document.

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   Next, an attribute called DIR is introduced, restricted to the values
   LTR (left-to-right) and RTL (right-to-left) and admitted by most ele-
   ments, for the indication of directionality in the context of bidi-
   rectional text (see 4.2.4 below for details).  Since any text and
   many other elements (e.g. tables) can logically be assigned a direc-
   tionality, almost all HTML elements admit the DIR attribute.  The DTD
   reflects this.  It is also intended that any new element introduced
   in later versions of HTML will admit the DIR attribute, unless there
   is a good reason not to do so.

   A new element called BDO (BIDI Override) is introduced, which
   requires the DIR attribute to specify whether the override is left-
   to-right or right-to-left.  This element is required for bidirec-
   tional text control; for detailed explanations, see section 4.2.4.

   The <Q> element is introduced to allow language-dependent rendering
   of short quotations depending on language and platform capability.
   As the following examples show, in particular the quotation marks
   surrounding the quotation are affected: "a quotation in English",
   `another, slightly better one', ,,a quotation in German'', << a quo-
   tation in French >>.  The contents of the <Q> element does not
   include quotation marks, they have to be added by the rendering pro-

        NOTE -- <Q> elements can be nested. Many languages use dif-
        ferent quotation styles for outer and inner quotations, and
        this should be respected by user-agents implementing this

   Many languages require superscripts for proper rendering: as an exam-
   ple, the French "Mlle Dupont" should have "lle" in superscript.  The
   <SUP> element, and its sibling <SUB>, are introduced to allow proper
   markup of such text.  <SUP> and <SUB> contents are restricted to
   PCDATA to avoid nesting problems.

   Finally, in many languages text justification is much more important
   than it is in Western languages, and justifies markup.  The ALIGN
   attribute, admitting values of LEFT, RIGHT, CENTER and JUSTIFY, is
   added to a selection of elements where it makes sense (block-like).
   If a user-agent chooses to have LEFT as a default for blocks of left-
   to-right directionality, it should use RIGHT for blocks of right-to-
   left directionality.

   In the DTD, the LANG and DIR attributes are grouped together in a
   parameter entity called attrs.  In addition, the ID and CLASS
   attributes from RFC 1942 [RFC1942] were added to attrs, as was done
   in the latter. The ID, and CLASS attributes are required for use with
   style sheets, and RFC 1942 defines them as follows:

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   ID      Used to define a document-wide identifier. This can be used
           for naming positions within documents as the destination of a
           hypertext link. It may also be used by style sheets for ren-
           dering an element in a unique style. An ID attribute value is
           an SGML NAME token. NAME tokens are formed by an initial let-
           ter followed by letters, digits, "-" and "." characters. The
           letters are restricted to A-Z and a-z.

   CLASS   A space separated list of SGML NAME tokens. CLASS names spec-
           ify that the element belongs to the corresponding named
           classes. It allows authors to distinguish different roles
           played by the same tag. The classes may be used by style
           sheets to provide different renderings as appropriate to
           these roles.

4.2.3. Cursive joining behaviour

   Markup is needed in some cases to force cursive joining behavior in
   contexts in which it would not normally occur, or to block it when it
   would normally occur.

   The zero-width joiner and non-joiner (&zwj; and &zwnj;) are used to
   control cursive joining behaviour.  For example, ARABIC LETTER HEH is
   used in isolation to abbreviate "Hijri" (the Islamic calendrical sys-
   tem); however, the initial form of the letter is desired, because the
   isolated form of HEH looks like the digit five as employed in Arabic
   script.  This is obtained by following the HEH with a zero-width
   joiner whose only effect is to provide context.  In Persian texts,
   there are cases where a letter that normally would join a subsequent
   letter in a cursive connection does not.  Here a zero-width non-
   joiner is used.

4.2.4. Bidirectional text

   Many languages are written in horizontal lines from left to right,
   while others are written from right to left.  When both writing
   directions are present, one talks of bidirectional text (BIDI for
   short). BIDI text requires markup in special circumstances where
   ambiguities as to the directionality of some characters have to be
   resolved.  This markup affects the ability to render BIDI text in a
   semantically legible fashion.  That is, without this special BIDI
   markup, cases arise which would prevent *any* rendering whatsoever
   that reflected the basic meaning of the text. Plain text may contain
   this markup (joining or BIDI) in the form of special-purpose charac-
   ters; in HTML, these are supplemented by SGML markup.

   BIDI is a complex issue, and implementers are advised to consult
   appropriate documentation such as [UNICODE]. Here, explanations are

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   given only as far as they are needed to understand the necessity of
   the features introduced and to define their exact semantics.

   The Unicode BIDI algorithm is based on a logical sequence of text
   characters and works mainly by reference to the implicit directional-
   ity of characters (e.g. Hebrew and Arabic characters are specified to
   be rendered from right to left, etc.).

   The left-to-right and right-to-left marks (&lrm; and &rlm;) are used
   to disambiguate directionality of neutral characters. For example,
   when a double quote sits between an Arabic and a Latin letter, its
   direction is ambiguous; if a directional mark is added on one side
   such that the quotation mark is surrounded by characters of only one
   directionality, the ambiguity is removed. These characters are like
   zero width spaces which have a directional property (but no word/line
   break property).

   Nested embeddings of contra-directional text runs, due to nested quo-
   tations or to the pasting of text from one BIDI context to another,
   is also a case where the implicit directionality of characters is not
   sufficient, requiring markup.  Also, it is frequently desirable to
   specify the basic directionality of a block of text. For these pur-
   poses, the DIR attribute is used.

   On block-type elements, the DIR attribute indicates the base direc-
   tionality of the text in the block; if omitted it is inherited from
   the parent element.   The default directionality of the overall HTML
   document is left-to-right.

   On inline elements, it makes the element start a new embedding level
   (to be explained below); if omitted the inline element does not start
   a new embedding level.

        NOTE -- the PRE, XMP and LISTING elements admit the DIR
        attribute, indicating that the contents should not be con-
        sidered as preformatted with respect to bidirectional lay-
        out. The BIDI algorithm still needs to be applied to each
        line of text.

   Following is an example of a case where embedding is needed, showing
   its effect:

        Given the following latin (upper case) and arabic (lower
        case) letters in backing store with the specified embed-

        </SPAN> zw </SPAN> EF </SPAN>

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        One gets the following rendering (with [] showing the
        directional transitions):

        [ AB [ wz [ CD ] yx ] EF ]

        On the other hand, without this markup and with a base
        direction of LTR one gets the following rendering:

        [ AB [ yx ] CD [ wz ] EF ]

        Notice that yx is on the left and wz on the right unlike
        the above case where the embedding levels are used.  With-
        out the embedding markup one has at most two levels: a base
        directional level and a single counterflow directional

   The DIR attribute on inline elements is equivalent to the formatting
   DING (202B) of ISO 10646.  The end tag of the element is equivalent
   to the POP DIRECTIONAL FORMATTING (202C) character.

   Directional override, as provided by the <BDO> element, is needed to
   deal with unusual short pieces of text in which directionality cannot
   be resolved from context in an unambiguous fashion. For example, it
   can be used to force left-to-right (or right-to-left) display of part
   numbers composed of Latin letters, digits and Hebrew letters.

   The effect of <BDO> is to force the directionality of all characters
   within it to the value of DIR, irrespective of their intrinsic direc-
   tional properties.  It is equivalent to using the LEFT-TO-RIGHT OVER-
   RIDE (202D) or RIGHT-TO-LEFT OVERRIDE (202E) characters of ISO 10646,
   the end tag again being equivalent to the POP DIRECTIONAL FORMATTING
   (202C) character.

        NOTE -- authors and authoring software writers should be
        aware that conflicts can arise if the DIR attribute is used
        on inline elements (including <BDO>) concurrently with the
        use of the corresponding ISO 10646 formatting characters.
        Preferably one or the other should be used exclusively; the
        markup method is better able to guarantee document struc-
        tural integrity, and alleviates some problems when editing
        bidirectional HTML text with a simple text editor, but some
        software may be more apt at using the 10646 characters.  If
        both methods are used, great care should be exercised to
        insure proper nesting of markup and directional embedding
        or override; otherwise, rendering results are undefined.

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5. Forms

5.1. DTD additions

   It is natural to expect input in any language in forms, as they pro-
   vide one of the only ways of obtaining user input. While this is pri-
   marily a UI issue, there are some things that should be specified at
   the HTML level to guide behavior and promote interoperability.

   To ensure full interoperability, it is necessary for the user agent
   (and the user) to have an indication of the character encoding(s)
   that the server providing a form will be able to handle upon submis-
   sion of the filled-in form.  Such an indication is provided by the
   ACCEPT-CHARSET attribute of the INPUT and TEXTAREA elements, modeled
   on the HTTP Accept-Charset header (see [HTTP-1.1]), which contains a
   space and/or comma delimited list of character sets acceptable to the
   server.  A user agent may want to somehow advise the user of the con-
   tents of this attribute, or to restrict his possibility to enter
   characters outside the repertoires of the listed character sets.

        NOTE -- The list of character sets is to be interpreted as
        an EXCLUSIVE-OR list; the server announces that it is ready
        to accept any ONE of these character encoding schemes for
        each part of a multipart entity.  The client may perform
        character encoding translation to satisfy the server if

        NOTE -- The default value for the ACCEPT-CHARSET attribute
        of an INPUT or TEXTAREA element is the reserved value
        "UNKNOWN".  A user agent may interpret that value as the
        character encoding scheme that was used to transmit the
        document containing that element.

5.2. Form submission

   The HTML 2.0 form submission mechanism, based on the "application/x-
   www-form-urlencoded" media type, is ill-equipped with regard to
   internationalization.  In fact, since URLs are restricted to ASCII
   characters, the mechanism is akward even for ISO-8859-1 text.  Sec-
   tion 2.2 of [RFC1738] specifies that octets may be encoded using the
   "%HH" notation, but text submitted from a form is composed of charac-
   ters, not octets.  Lacking a specification of a character encoding
   scheme, the "%HH" notation has no well-defined meaning.

   The best solution is to use the "multipart/form-data" media type
   described in [RFC1867] with the POST method of form submission.  This

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   mechanism encapsulates the value part of each name-value pair in a
   body-part of a multipart MIME body that is sent as the HTTP entity;
   each body part can be labeled with an appropriate Content-Type,
   including if necessary a charset parameter that specifies the charac-
   ter encoding scheme.  The changes to the DTD necessary to support
   this method of form submission have been incorporated in the DTD
   included in this specification.

   A less satisfactory solution is to add a MIME charset parameter to
   the "application/x-www-form-urlencoded" media type specifier sent
   along with a POST method form submission, with the understanding that
   the URL encoding of [RFC1738] is applied on top of the specified
   character encoding, as a kind of implicit Content-Transfer-Encoding.

   One problem with both solutions above is that current browsers do not
   generally allow for bookmarks to specify the POST method; this should
   be improved.  Conversely, the GET method could be used with the form
   data transmitted in the body instead of in the URL.  Nothing in the
   protocol seems to prevent it, but no implementations appear to exist
   at present.

   How the user agent determines the encoding of the text entered by the
   user is outside the scope of this specification.

        NOTE -- Designers of forms and their handling scripts
        should be aware of an important caveat: when the default
        value of a field (the VALUE attribute) is returned upon
        form submission (i.e. the user did not modify this value),
        it cannot be guaranteed to be transmitted as a sequence of
        octets identical to that in the source document -- only as
        a possibly different but valid encoding of the same
        sequence of text elements.  This may be true even if the
        encoding of the document containing the form and that used
        for submission are the same.

        Differences can occur when a sequence of characters can be
        represented by various sequences of octets, and also when a
        composite sequence (a base character plus one or more com-
        bining diacritics) can be represented by either a different
        but equivalent composite sequence or by a fully precomposed
        character. For instance, the UCS-2 sequence 00EA+0232
        DOT BELOW) may be transformed into 1EC7 (LATIN SMALL LETTER
        ACCENT + COMBINING DOT BELOW), as well as into other equiv-
        alent composite sequences.

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6. Miscellaneous

   Proper interpretation of a text document requires that the character
   encoding scheme be known.  Current HTTP servers, however, do not gen-
   erally include an appropriate charset parameter with the Content-Type
   header.  This is bad behaviour[2], and as such strongly discouraged,
   but some preventive measures can be taken to minimize the detrimental

   In the case where a document is accessed from a hyperlink in an ori-
   gin HTML document, a CHARSET attribute is added to the attribute list
   of elements with link semantics (A and LINK), specifically by adding
   it to the linkExtraAttributes entity.  The value of that attribute is
   to be considered a hint to the User Agent as to the character encod-
   ing scheme used by the ressource pointed to by the hyperlink; it
   should be the appropriate value of the MIME charset parameter for
   that ressource.

   In any document, it is possible to include an indication of the
   encoding scheme like the following, as early as possible within the
   HEAD of the document:

    <META HTTP-EQUIV="Content-Type"
     CONTENT="text/html; charset=ISO-2022-JP">

   This is not foolproof, but will work if the encoding scheme is such
   that ASCII characters stand for themselves at least until the META
   element is parsed.  Note that there are better ways for a server to
   obtain character encoding information, instead of the unreliable
   <META> above; see [NICOL2] for some details and a proposal.

   For definiteness, the "charset" parameter received from the source of
   the document should be considered the most authoritative, followed in
   order of preference by the contents of a META element such as the
   above, and finally the CHARSET parameter of the anchor that was fol-
   lowed (if any).

   When HTML text is transmitted directly in UCS-2 or UCS-4 form, the
   question of byte order arises: does the high-order byte of each
   multi-byte character come first or last?  For definiteness, this
   specification recommends that UCS-2 and UCS-4 be transmitted in big-
  2 This bad behaviour is even encouraged by the continued
existence of browsers that declare an unrecognized media
type when they receive a charset parameter.  User agent
implementators are strongly encouraged to make their soft-
ware tolerant of this parameter, even if they cannot take
advantage of it.

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   endian byte order (high order byte first), which corresponds to the
   established network byte order for two- and four-byte quantities, to
   the Unicode recommendation for serialized text data and to RFC 1641.
   Furthermore, to maximize chances of proper interpretation, it is rec-
   ommended that documents transmitted as UCS-2 or UCS-4 always begin
   with a ZERO-WIDTH NON-BREAKING SPACE character (hexadecimal FEFF or
   0000FEFF) which, when byte-reversed becomes number FFFE or FFFE0000,
   a character guaranteed to be never assigned.  Thus, a user-agent
   receiving an FFFE as the first octets of a text would know that bytes
   have to be reversed for the remainder of the text.

   There exist so-called UCS Transformation Formats than can be used to
   transmit UCS data, in addition to UCS-2 and UCS-4.  UTF-7 [RFC1642]
   and UTF-8 [UTF-8] have favorable properties (no byte-ordering prob-
   lem, different flavours of ASCII compatibility) that make them worthy
   of consideration, especially for transmission of multilingual text.
   Another encoding scheme, MNEM [RFC1345], also has interesting proper-
   ties and the capability to transmit the full UCS.  The UTF-1 trans-
   formation format of ISO 10646:1993 (registered by IANA as
   ISO-10646-UTF-1), has been removed from ISO 10646 by amendment 4, and
   should not be used.

   The SOFT HYPHEN character (U+00AD) needs a little attention from
   user-agent implementers.  It is present in many character sets
   (including the whole ISO 8859 series and, of course, ISO 10646), and
   has semantics different from the plain HYPHEN.  If not used for
   hyphenation, the soft hyphen must be completely ignored.  For exam-
   ple, "rec&shy;ord" should display as "record", should match a search
   for "record", and should sort as "record".  Non-observance of these
   semantics effectively discourages its use on the World Wide Web, even
   with software that does support it.

7. HTML Public Text


   This section contains a DTD for HTML based on the HTML 2.0 DTD of RFC
   1866, incorporating the changes for file upload as specified in RFC
   1867, and the changes deriving from this document.

   <!--    html.dtd

           Document Type Definition for the HyperText Markup Language,
           extended for internationalisation (HTML DTD)

           Last revised: 96/05/27

        Authors: Daniel W. Connolly <connolly@w3.org>

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                    Francois Yergeau <yergeau@alis.com>
        See Also: html.decl, html-1.dtd

   <!ENTITY % HTML.Version
           "-//IETF//DTD HTML//EN"

           -- Typical usage:

               <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">

   <!--============ Feature Test Entities ========================-->

   <!ENTITY % HTML.Recommended "IGNORE"
        -- Certain features of the language are necessary for
           compatibility with widespread usage, but they may
           compromise the structural integrity of a document.
           This feature test entity enables a more prescriptive
           document type definition that eliminates
           those features.

   <![ %HTML.Recommended [
           <!ENTITY % HTML.Deprecated "IGNORE">

   <!ENTITY % HTML.Deprecated "INCLUDE"
        -- Certain features of the language are necessary for
           compatibility with earlier versions of the specification,
           but they tend to be used and implemented inconsistently,
           and their use is deprecated. This feature test entity
           enables a document type definition that eliminates
           these features.

   <!ENTITY % HTML.Highlighting "INCLUDE"
        -- Use this feature test entity to validate that a
           document uses no highlighting tags, which may be
           ignored on minimal implementations.

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           -- Use this feature test entity to validate that a document
              contains no forms, which may not be supported in minimal

   <!--============== Imported Names ==============================-->

   <!ENTITY % Content-Type "CDATA"
           -- meaning an internet media type
              (aka MIME content type, as per RFC1521)

   <!ENTITY % HTTP-Method "GET | POST"
           -- as per HTTP specification, RFC1945

   <!--========= DTD "Macros" =====================-->

   <!ENTITY % heading "H1|H2|H3|H4|H5|H6">

   <!ENTITY % list " UL | OL | DIR | MENU " >

   <!ENTITY % attrs -- common attributes for elements --
            "LANG  NAME      #IMPLIED  -- RFC 1766 language tag --
             DIR  (ltr|rtl)  #IMPLIED  -- text directionnality --
             ID      ID      #IMPLIED  -- element identifier (from RFC1942) --
             CLASS   NAMES   #IMPLIED  -- for subclassing elements (from RFC1942) --">

   <!ENTITY % just -- an attribute for text justification --
            "ALIGN  (left|right|center|justify)  #IMPLIED"
            -- default is left for ltr paragraphs, right for rtl -- >

   <!--======= Character mnemonic entities =================-->

     "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML">

   <!ENTITY amp CDATA "&#38;"     -- ampersand          -->
   <!ENTITY gt CDATA "&#62;"      -- greater than       -->
   <!ENTITY lt CDATA "&#60;"      -- less than          -->
   <!ENTITY quot CDATA "&#34;"    -- double quote       -->

   <!--Entities for language-dependent presentation (BIDI and contextual analysis) -->
   <!ENTITY zwnj CDATA "&#8204;"-- zero width non-joiner-->
   <!ENTITY zwj  CDATA "&#8205;"-- zero width joiner-->
   <!ENTITY lrm  CDATA "&#8206;"-- left-to-right mark-->

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   <!ENTITY rlm  CDATA "&#8207;"-- right-to-left mark-->

   <!--========= SGML Document Access (SDA) Parameter Entities =====-->

   <!-- HTML contains SGML Document Access (SDA) fixed attributes
   in support of easy transformation to the International Committee
   for Accessible Document Design (ICADD) DTD
         "-//EC-USA-CDA/ICADD//DTD ICADD22//EN".
   ICADD applications are designed to support usable access to
   structured information by print-impaired individuals through
   Braille, large print and voice synthesis.  For more information on
           - ISO 12083:1993, Annex A.8, Facilities for Braille,
          large print and computer voice
           - ICADD ListServ
           - Usenet news group bit.listserv.easi
           - Recording for the Blind, +1 800 221 4792

          -- one to one mapping        -->
          -- context-sensitive mapping -->
          -- generated text prefix     -->
          -- generated text suffix     -->
          -- suspend transform process -->

   <!--========== Text Markup =====================-->

   <![ %HTML.Highlighting [

   <!ENTITY % font " TT | B | I ">

   <!ENTITY % phrase "EM | STRONG | CODE | SAMP | KBD | VAR | CITE ">

   <!ENTITY % text "#PCDATA|A|IMG|BR|%phrase|%font|SPAN|Q|BDO|SUP|SUB">

   <!ELEMENT (%font;|%phrase) - - (%text)*>
           %SDAFORM; "Lit"

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           %SDAFORM; "B"
   <!ATTLIST ( I | EM | CITE )
           %SDAFORM; "It"

   <!-- <TT>       Typewriter text                         -->
   <!-- <B>        Bold text                               -->
   <!-- <I>        Italic text                             -->

   <!-- <EM>       Emphasized phrase                       -->
   <!-- <STRONG>   Strong emphasis                         -->
   <!-- <CODE>     Source code phrase                      -->
   <!-- <SAMP>     Sample text or characters               -->
   <!-- <KBD>      Keyboard phrase, e.g. user input        -->
   <!-- <VAR>      Variable phrase or substitutable        -->
   <!-- <CITE>     Name or title of cited work             -->

   <!ENTITY % pre.content "#PCDATA|A|HR|BR|%font|%phrase|SPAN|BDO">



           %SDAPREF; "&#RE;"

   <!-- <BR>       Line break      -->

   <!ELEMENT SPAN - - (%text)*>
           %SDAFORM; "other #Attlist"

   <!-- <SPAN>             Generic inline container  -->
   <!-- <SPAN DIR=...>     New counterflow embedding -->
   <!-- <SPAN LANG="...">  Language of contents      -->

   <!ELEMENT Q - - (%text)*>
           %SDAPREF; '"'

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           %SDASUFF; '"'

   <!-- <Q>         Short quotation              -->
   <!-- <Q LANG=xx> Language of quotation is xx  -->
   <!-- <Q DIR=...> New conterflow embedding     -->

   <!ELEMENT BDO - - (%text)+>
           LANG   NAME      #IMPLIED
           DIR    (ltr|rtl) #REQUIRED
           %SDAPREF "Bidi Override #Attval(DIR): "
           %SDASUFF "End Bidi"

   <!-- <BDO DIR=...>   Override directionality of text to value of DIR -->
   <!-- <BDO LANG=...>  Language of contents                            -->

           %SDAPREF "Superscript(#content)"
           %SDAPREF "Subscript(#content)"

   <!-- <SUP>      Superscript              -->
   <!-- <SUB>      Subscript                -->

   <!--========= Link Markup ======================-->

   <!ENTITY % linkType "NAMES">

   <!ENTITY % linkExtraAttributes
           "REL %linkType #IMPLIED
           REV %linkType #IMPLIED

   <![ %HTML.Recommended [
           <!ENTITY % A.content   "(%text)*"
           -- <H1><a name="xxx">Heading</a></H1>
                   is preferred to

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              <a name="xxx"><H1>Heading</H1></a>

   <!ENTITY % A.content   "(%heading|%text)*">

   <!ELEMENT A     - - %A.content -(A)>
           %SDAPREF; "<Anchor: #AttList>"
   <!-- <A>       Anchor; source/destination of link -->
   <!-- <A NAME="..."> Name of this anchor           -->
   <!-- <A HREF="..."> Address of link destination        -->
   <!-- <A URN="...">  Permanent address of destination   -->
   <!-- <A REL=...>    Relationship to destination        -->
   <!-- <A REV=...>    Relationship of destination to this     -->
   <!-- <A TITLE="...">     Title of destination (advisory)         -->
   <!-- <A METHODS="...">   Operations on destination (advisory)    -->
   <!-- <A CHARSET="...">   Charset of destination (advisory)  -->
   <!-- <A LANG="...">     Language of contents btw <A> and </A>   -->
   <!-- <A DIR=...>        Contents is a new counterflow embedding -->

   <!--========== Images ==========================-->

           ALIGN (top|middle|bottom) #IMPLIED
           %SDAPREF; "<Fig><?SDATrans Img: #AttList>#AttVal(Alt)</Fig>"

   <!-- <IMG>              Image; icon, glyph or illustration      -->
   <!-- <IMG SRC="...">    Address of image object                 -->
   <!-- <IMG ALT="...">    Textual alternative                     -->
   <!-- <IMG ALIGN=...>    Position relative to text               -->
   <!-- <IMG LANG=...>     Image contains "text" in that language  -->
   <!-- <IMG DIR=rtl>      Inline image acts as a right-to-left
                           embedding w/r to BIDI algorithm         -->
   <!-- <IMG ISMAP>        Each pixel can be a link                -->

   <!--========== Paragraphs=======================-->

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   <!ELEMENT P     - O (%text)*>
           %SDAFORM; "Para"

   <!-- <P>             Paragraph                           -->
   <!-- <P LANG="...">  Language of paragraph text          -->
   <!-- <P DIR=...>     Base directionality of paragraph    -->
   <!-- <P ALIGN=...>   Paragraph alignment (justification) -->

   <!--========== Headings, Titles, Sections ===============-->

           %SDAPREF; "&#RE;&#RE;"

   <!-- <HR>       Horizontal rule -->

   <!ELEMENT ( %heading )  - -  (%text;)*>
           %SDAFORM; "H1"
           %SDAFORM; "H2"
           %SDAFORM; "H3"
           %SDAFORM; "H4"
           %SDAFORM; "H5"

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           %SDAFORM; "H6"

   <!-- <H1>       Heading, level 1 -->
   <!-- <H2>       Heading, level 2 -->
   <!-- <H3>       Heading, level 3 -->
   <!-- <H4>       Heading, level 4 -->
   <!-- <H5>       Heading, level 5 -->
   <!-- <H6>       Heading, level 6 -->

   <!--========== Text Flows ======================-->

   <![ %HTML.Forms [
           <!ENTITY % block.forms "BLOCKQUOTE | FORM | ISINDEX">

   <!ENTITY % block.forms "BLOCKQUOTE">

   <![ %HTML.Deprecated [
           <!ENTITY % preformatted "PRE | XMP | LISTING">

   <!ENTITY % preformatted "PRE">

   <!ENTITY % block "P | %list | DL
           | %preformatted
           | %block.forms">

   <!ENTITY % flow "(%text|%block)*">

   <!ENTITY % pre.content "#PCDATA | A | HR | BR | SPAN | BDO">
   <!ELEMENT PRE - - (%pre.content)*>
           WIDTH NUMBER #implied
           %SDAFORM; "Lit"

   <!-- <PRE>              Preformatted text                    -->
   <!-- <PRE WIDTH=...>    Maximum characters per line          -->
   <!-- <PRE DIR=...>      Base direction of preformatted block -->
   <!-- <PRE LANG=...>     Language of contents                 -->

   <![ %HTML.Deprecated [

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   <!ENTITY % literal "CDATA"
           -- historical, non-conforming parsing mode where
              the only markup signal is the end tag
              in full

   <!ELEMENT (XMP|LISTING) - -  %literal>
           %SDAFORM; "Lit"
           %SDAPREF; "Example:&#RE;"
           %SDAFORM; "Lit"
           %SDAPREF; "Listing:&#RE;"

   <!-- <XMP>              Example section         -->
   <!-- <LISTING>          Computer listing        -->

   <!ELEMENT PLAINTEXT - O %literal>
   <!-- <PLAINTEXT>        Plain text passage      -->

           %SDAFORM; "Lit"

   <!--========== Lists ==================-->

   <!ELEMENT DL    - -  (DT | DD)+>
           %SDAFORM; "List"
           %SDAPREF; "Definition List:"

   <!ELEMENT DT    - O (%text)*>
           %SDAFORM; "Term"

   <!ELEMENT DD    - O %flow>

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           %SDAFORM; "LItem"

   <!-- <DL>               Definition list, or glossary    -->
   <!-- <DL COMPACT>       Compact style list              -->
   <!-- <DT>               Term in definition list         -->
   <!-- <DD>               Definition of term              -->

   <!ELEMENT (OL|UL) - -  (LI)+>
           %SDAFORM; "List"
           %SDAFORM; "List"
   <!-- <UL>               Unordered list                  -->
   <!-- <UL COMPACT>       Compact list style              -->
   <!-- <OL>               Ordered, or numbered list       -->
   <!-- <OL COMPACT>       Compact list style              -->

   <!ELEMENT (DIR|MENU) - -  (LI)+ -(%block)>
           %SDAFORM; "List"
           %SDAPREF; "<LHead>Directory</LHead>"
           %SDAFORM; "List"
           %SDAPREF; "<LHead>Menu</LHead>"

   <!-- <DIR>              Directory list                  -->
   <!-- <DIR COMPACT>      Compact list style              -->
   <!-- <MENU>             Menu list                       -->

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   <!-- <MENU COMPACT>     Compact list style              -->

   <!ELEMENT LI    - O %flow>
           %SDAFORM; "LItem"

   <!-- <LI>               List item                       -->

   <!--========== Document Body ===================-->

   <![ %HTML.Recommended [
        <!ENTITY % body.content "(%heading|%block|HR|ADDRESS|IMG)*"
        -- <h1>Heading</h1>
           <p>Text ...
             is preferred to
           Text ...

   <!ENTITY % body.content "(%heading | %text | %block |
                        HR | ADDRESS)*">

   <!ELEMENT BODY O O  %body.content>

   <!-- <BODY>          Document body                -->
   <!-- <BODY DIR=...>  Base direction of whole body -->
   <!-- <BODY LANG=...> Language of contents         -->

   <!ELEMENT BLOCKQUOTE - - %body.content>
           %SDAFORM; "BQ"

   <!-- <BLOCKQUOTE>       Quoted passage  -->

   <!ELEMENT ADDRESS - - (%text|P)*>

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           %SDAFORM; "Lit"
           %SDAPREF; "Address:&#RE;"

   <!-- <ADDRESS> Address, signature, or byline -->

   <!--======= Forms ====================-->

   <![ %HTML.Forms [

   <!ELEMENT FORM - - %body.content -(FORM) +(INPUT|SELECT|TEXTAREA)>
           METHOD (%HTTP-Method) GET
           ENCTYPE %Content-Type; "application/x-www-form-urlencoded"
           %SDAPREF; "<Para>Form:</Para>"
           %SDASUFF; "<Para>Form End.</Para>"

   <!-- <FORM>                     Fill-out or data-entry form     -->
   <!-- <FORM ACTION="...">        Address for completed form      -->
   <!-- <FORM METHOD=...>          Method of submitting form       -->
   <!-- <FORM ENCTYPE="...">       Representation of form data     -->
   <!-- <FORM DIR=...>             Base direction of form          -->
   <!-- <FORM LANG=...>            Language of contents            -->

                           RADIO | SUBMIT | RESET |
                           IMAGE | HIDDEN | FILE )">
        TYPE %InputType TEXT
        ALIGN (top|middle|bottom) #IMPLIED
           ACCEPT CDATA #IMPLIED --list of content types --
           ACCEPT-CHARSET CDATA #IMPLIED --list of charsets accepted by server --
           %SDAPREF; "Input: "

   <!-- <INPUT>               Form input datum        -->

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   <!-- <INPUT TYPE=...>           Type of input interaction    -->
   <!-- <INPUT NAME=...>           Name of form datum           -->
   <!-- <INPUT VALUE="...">   Default/initial/selected value -->
   <!-- <INPUT SRC="...">          Address of image        -->
   <!-- <INPUT CHECKED>            Initial state is "on"        -->
   <!-- <INPUT SIZE=...>           Field size hint         -->
   <!-- <INPUT MAXLENGTH=...>      Data length maximum          -->
   <!-- <INPUT ALIGN=...>          Image alignment         -->
   <!-- <INPUT ACCEPT="...">         List of desired media types    -->
   <!-- <INPUT ACCEPT-CHARSET="..."> List of acceptable charsets    -->

           %SDAFORM; "List"
           "<LHead>Select #AttVal(Multiple)</LHead>"

   <!-- <SELECT>            Selection of option(s)        -->
   <!-- <SELECT NAME=...>        Name of form datum       -->
   <!-- <SELECT SIZE=...>        Options displayed at a time   -->
   <!-- <SELECT MULTIPLE>        Multiple selections allowed   -->

           %SDAFORM; "LItem"
           "Option: #AttVal(Value) #AttVal(Selected)"

   <!-- <OPTION>            A selection option       -->
   <!-- <OPTION SELECTED>        Initial state            -->
   <!-- <OPTION VALUE="...">     Form datum value for this option-->

           ACCEPT-CHARSET CDATA #IMPLIED -- list of charsets accepted by server --

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           %SDAFORM; "Para"
           %SDAPREF; "Input Text -- #AttVal(Name): "

   <!-- <TEXTAREA>               An area for text input        -->
   <!-- <TEXTAREA NAME=...> Name of form datum       -->
   <!-- <TEXTAREA ROWS=...> Height of area           -->
   <!-- <TEXTAREA COLS=...> Width of area            -->


   <!--======= Document Head ======================-->

   <![ %HTML.Recommended [
        <!ENTITY % head.extra "">
   <!ENTITY % head.extra "& NEXTID?">

   <!ENTITY % head.content "TITLE & ISINDEX? & BASE? %head.extra">

   <!ELEMENT HEAD O O  (%head.content) +(META|LINK)>
           %attrs;           >

   <!-- <HEAD>     Document head   -->

           %SDAFORM; "Ti"    >

   <!-- <TITLE>    Title of document -->

           %SDAPREF; "Linked to : #AttVal (TITLE) (URN) (HREF)>"    >

   <!-- <LINK>         Link from this document            -->
   <!-- <LINK HREF="...">   Address of link destination        -->
   <!-- <LINK URN="...">    Lasting name of destination        -->
   <!-- <LINK REL=...> Relationship to destination        -->
   <!-- <LINK REV=...> Relationship of destination to this     -->
   <!-- <LINK TITLE="...">  Title of destination (advisory)         -->
   <!-- <LINK CHARSET="..."> Charset of destination (advisory)      -->

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   <!-- <LINK METHODS="..."> Operations allowed (advisory)          -->

      "<Para>[Document is indexed/searchable.]</Para>">

   <!-- <ISINDEX>          Document is a searchable index          -->

           HREF CDATA #REQUIRED     >

   <!-- <BASE>             Base context document                   -->
   <!-- <BASE HREF="...">  Address for this document               -->

           N CDATA #REQUIRED     >

   <!-- <NEXTID>       Next ID to use for link name       -->
   <!-- <NEXTID N=...> Next ID to use for link name       -->

           NAME        NAME    #IMPLIED
           CONTENT     CDATA   #REQUIRED    >

   <!-- <META>                     Generic Meta-information        -->
   <!-- <META HTTP-EQUIV=...>      HTTP response header name       -->
   <!-- <META NAME=...>          Meta-information name           -->
   <!-- <META CONTENT="...">       Associated information          -->

   <!--======= Document Structure =================-->

   <![ %HTML.Deprecated [
           <!ENTITY % html.content "HEAD, BODY, PLAINTEXT?">
   <!ENTITY % html.content "HEAD, BODY">

   <!ELEMENT HTML O O  (%html.content)>
   <!ENTITY % version.attr "VERSION CDATA #FIXED '%HTML.Version;'">


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           %SDAFORM; "Book"

   <!-- <HTML>              HTML Document  -->

7.2. SGML Declaration for HTML

   <!SGML  "ISO 8879:1986"
        SGML Declaration for HyperText Markup Language version 2.x
           (HTML 2.x = HTML 2.0 + i18n).


            BASESET  "ISO Registration Number 177//CHARSET
                      ISO/IEC 10646-1:1993 UCS-4 with
                      implementation level 3//ESC 2/5 2/15 4/6"
            DESCSET  0   9     UNUSED
                     9   2     9
                     11  2     UNUSED
                     13  1     13
                     14  18    UNUSED
                     32  95    32
                     127 1     UNUSED
                     128 32    UNUSED
                     160 2147483486 160

                   TOTALCAP        150000
                   GRPCAP          150000
             ENTCAP         150000

            SHUNCHAR CONTROLS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
              17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 127
            BASESET  "ISO 646:1983//CHARSET
                      International Reference Version
                      (IRV)//ESC 2/5 4/0"
            DESCSET  0 128 0

                     RE            13
                     RS            10
                     SPACE         32
                     TAB SEPCHAR    9

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            NAMING   LCNMSTRT ""
                     UCNMSTRT ""
                     LCNMCHAR ".-"
                     UCNMCHAR ".-"
                     NAMECASE GENERAL YES
                              ENTITY  NO
                     SHORTREF SGMLREF
            NAMES    SGMLREF
                     ATTSPLEN 2100
                     LITLEN   1024
                     NAMELEN  72    -- somewhat arbitrary; taken from
                                   internet line length conventions --
                     PILEN    1024
                     TAGLVL   100
                     TAGLEN   2100
                     GRPGTCNT 150
                     GRPCNT   64

       DATATAG  NO
       RANK     NO
       SIMPLE   NO
       CONCUR   NO
       SUBDOC   NO
       FORMAL   YES
     APPINFO    "SDA"  -- conforming SGML Document Access application

7.3. ISO Latin 1 entity set

   The following public text lists each of the characters specified in
   the Added Latin 1 entity set, along with its name, syntax for use,
   and description. This list is derived from ISO Standard
   8879:1986//ENTITIES Added Latin 1//EN. HTML includes the entire
   entity set, and adds entities for all missing characters in the right
   part of ISO-8859-1.

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    <!-- (C) International Organization for Standardization 1986
         Permission to copy in any form is granted for use with
         conforming SGML systems and applications as defined in
         ISO 8879, provided this notice is included in all copies.
    <!-- Character entity set. Typical invocation:
         <!ENTITY % ISOlat1 PUBLIC
           "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML">
    <!ENTITY nbsp   CDATA "&#160;" -- no-break space -->
    <!ENTITY iexcl  CDATA "&#161;" -- inverted exclamation mark -->
    <!ENTITY cent   CDATA "&#162;" -- cent sign -->
    <!ENTITY pound  CDATA "&#163;" -- pound sterling sign -->
    <!ENTITY curren CDATA "&#164;" -- general currency sign -->
    <!ENTITY yen    CDATA "&#165;" -- yen sign -->
    <!ENTITY brvbar CDATA "&#166;" -- broken (vertical) bar -->
    <!ENTITY sect   CDATA "&#167;" -- section sign -->
    <!ENTITY uml    CDATA "&#168;" -- umlaut (dieresis) -->
    <!ENTITY copy   CDATA "&#169;" -- copyright sign -->
    <!ENTITY ordf   CDATA "&#170;" -- ordinal indicator, feminine -->
    <!ENTITY laquo  CDATA "&#171;" -- angle quotation mark, left -->
    <!ENTITY not    CDATA "&#172;" -- not sign -->
    <!ENTITY shy    CDATA "&#173;" -- soft hyphen -->
    <!ENTITY reg    CDATA "&#174;" -- registered sign -->
    <!ENTITY macr   CDATA "&#175;" -- macron -->
    <!ENTITY deg    CDATA "&#176;" -- degree sign -->
    <!ENTITY plusmn CDATA "&#177;" -- plus-or-minus sign -->
    <!ENTITY sup2   CDATA "&#178;" -- superscript two -->
    <!ENTITY sup3   CDATA "&#179;" -- superscript three -->
    <!ENTITY acute  CDATA "&#180;" -- acute accent -->
    <!ENTITY micro  CDATA "&#181;" -- micro sign -->
    <!ENTITY para   CDATA "&#182;" -- pilcrow (paragraph sign) -->
    <!ENTITY middot CDATA "&#183;" -- middle dot -->
    <!ENTITY cedil  CDATA "&#184;" -- cedilla -->
    <!ENTITY sup1   CDATA "&#185;" -- superscript one -->
    <!ENTITY ordm   CDATA "&#186;" -- ordinal indicator, masculine -->
    <!ENTITY raquo  CDATA "&#187;" -- angle quotation mark, right -->
    <!ENTITY frac14 CDATA "&#188;" -- fraction one-quarter -->
    <!ENTITY frac12 CDATA "&#189;" -- fraction one-half -->
    <!ENTITY frac34 CDATA "&#190;" -- fraction three-quarters -->
    <!ENTITY iquest CDATA "&#191;" -- inverted question mark -->
    <!ENTITY Agrave CDATA "&#192;" -- capital A, grave accent -->
    <!ENTITY Aacute CDATA "&#193;" -- capital A, acute accent -->
    <!ENTITY Acirc  CDATA "&#194;" -- capital A, circumflex accent -->
    <!ENTITY Atilde CDATA "&#195;" -- capital A, tilde -->
    <!ENTITY Auml   CDATA "&#196;" -- capital A, dieresis or umlaut mark -->
    <!ENTITY Aring  CDATA "&#197;" -- capital A, ring -->

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    <!ENTITY AElig  CDATA "&#198;" -- capital AE diphthong (ligature) -->
    <!ENTITY Ccedil CDATA "&#199;" -- capital C, cedilla -->
    <!ENTITY Egrave CDATA "&#200;" -- capital E, grave accent -->
    <!ENTITY Eacute CDATA "&#201;" -- capital E, acute accent -->
    <!ENTITY Ecirc  CDATA "&#202;" -- capital E, circumflex accent -->
    <!ENTITY Euml   CDATA "&#203;" -- capital E, dieresis or umlaut mark -->
    <!ENTITY Igrave CDATA "&#204;" -- capital I, grave accent -->
    <!ENTITY Iacute CDATA "&#205;" -- capital I, acute accent -->
    <!ENTITY Icirc  CDATA "&#206;" -- capital I, circumflex accent -->
    <!ENTITY Iuml   CDATA "&#207;" -- capital I, dieresis or umlaut mark -->
    <!ENTITY ETH    CDATA "&#208;" -- capital Eth, Icelandic -->
    <!ENTITY Ntilde CDATA "&#209;" -- capital N, tilde -->
    <!ENTITY Ograve CDATA "&#210;" -- capital O, grave accent -->
    <!ENTITY Oacute CDATA "&#211;" -- capital O, acute accent -->
    <!ENTITY Ocirc  CDATA "&#212;" -- capital O, circumflex accent -->
    <!ENTITY Otilde CDATA "&#213;" -- capital O, tilde -->
    <!ENTITY Ouml   CDATA "&#214;" -- capital O, dieresis or umlaut mark -->
    <!ENTITY times  CDATA "&#215;" -- multiply sign -->
    <!ENTITY Oslash CDATA "&#216;" -- capital O, slash -->
    <!ENTITY Ugrave CDATA "&#217;" -- capital U, grave accent -->
    <!ENTITY Uacute CDATA "&#218;" -- capital U, acute accent -->
    <!ENTITY Ucirc  CDATA "&#219;" -- capital U, circumflex accent -->
    <!ENTITY Uuml   CDATA "&#220;" -- capital U, dieresis or umlaut mark -->
    <!ENTITY Yacute CDATA "&#221;" -- capital Y, acute accent -->
    <!ENTITY THORN  CDATA "&#222;" -- capital Thorn, Icelandic -->
    <!ENTITY szlig  CDATA "&#223;" -- small sharp s, German (sz ligature) -->
    <!ENTITY agrave CDATA "&#224;" -- small a, grave accent -->
    <!ENTITY aacute CDATA "&#225;" -- small a, acute accent -->
    <!ENTITY acirc  CDATA "&#226;" -- small a, circumflex accent -->
    <!ENTITY atilde CDATA "&#227;" -- small a, tilde -->
    <!ENTITY auml   CDATA "&#228;" -- small a, dieresis or umlaut mark -->
    <!ENTITY aring  CDATA "&#229;" -- small a, ring -->
    <!ENTITY aelig  CDATA "&#230;" -- small ae diphthong (ligature) -->
    <!ENTITY ccedil CDATA "&#231;" -- small c, cedilla -->
    <!ENTITY egrave CDATA "&#232;" -- small e, grave accent -->
    <!ENTITY eacute CDATA "&#233;" -- small e, acute accent -->
    <!ENTITY ecirc  CDATA "&#234;" -- small e, circumflex accent -->
    <!ENTITY euml   CDATA "&#235;" -- small e, dieresis or umlaut mark -->
    <!ENTITY igrave CDATA "&#236;" -- small i, grave accent -->
    <!ENTITY iacute CDATA "&#237;" -- small i, acute accent -->
    <!ENTITY icirc  CDATA "&#238;" -- small i, circumflex accent -->
    <!ENTITY iuml   CDATA "&#239;" -- small i, dieresis or umlaut mark -->
    <!ENTITY eth    CDATA "&#240;" -- small eth, Icelandic -->
    <!ENTITY ntilde CDATA "&#241;" -- small n, tilde -->
    <!ENTITY ograve CDATA "&#242;" -- small o, grave accent -->
    <!ENTITY oacute CDATA "&#243;" -- small o, acute accent -->
    <!ENTITY ocirc  CDATA "&#244;" -- small o, circumflex accent -->
    <!ENTITY otilde CDATA "&#245;" -- small o, tilde -->

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    <!ENTITY ouml   CDATA "&#246;" -- small o, dieresis or umlaut mark -->
    <!ENTITY divide CDATA "&#247;" -- divide sign -->
    <!ENTITY oslash CDATA "&#248;" -- small o, slash -->
    <!ENTITY ugrave CDATA "&#249;" -- small u, grave accent -->
    <!ENTITY uacute CDATA "&#250;" -- small u, acute accent -->
    <!ENTITY ucirc  CDATA "&#251;" -- small u, circumflex accent -->
    <!ENTITY uuml   CDATA "&#252;" -- small u, dieresis or umlaut mark -->
    <!ENTITY yacute CDATA "&#253;" -- small y, acute accent -->
    <!ENTITY thorn  CDATA "&#254;" -- small thorn, Icelandic -->
    <!ENTITY yuml   CDATA "&#255;" -- small y, dieresis or umlaut mark -->


   [BRYAN88]      M. Bryan, "SGML -- An Author's Guide to the Standard
                  Generalized Markup Language", Addison-Wesley, Reading,

   [ERCS]         Extended Reference Concrete Syntax for SGML.

   [GOLD90]       C. F. Goldfarb, "The SGML Handbook", Y. Rubinsky, Ed.,
                  Oxford University Press, 1990.

   [HTTP-1.1]     R.T. Fielding, H. Frystyk Nielsen, and T. Berners-Lee,
                  "Hypertext Transfer Protocol -- HTTP/1.1", Work in
                  progress (draft-ietf-http-v11-spec-03.txt), MIT/LCS,
                  May 1996.

   [ISO-639]      ISO 639:1988. Codes pour la représentation des noms de
                  langue.  Technical content in

   [ISO-3166]     ISO 3166:1993. Codes pour la représentation des noms
                  de pays.

   [ISO-8601]     ISO 8601:1988.  Éléments de données et formats
                  d'échange -- Échange d'information -- Représentation
                  de la date et de l'heure.

   [ISO-8859-1]   ISO 8859-1:1987.  International Standard -- Informa-
                  tion Processing -- 8-bit Single-Byte Coded Graphic
                  Character Sets -- Part 1: Latin Alphabet No. 1.

   [ISO-8879]     ISO 8879:1986. International Standard -- Information
                  Processing -- Text and Office Systems -- Standard Gen-
                  eralized Markup Language (SGML).

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   [ISO-10646]    ISO/IEC 10646-1:1993. International Standard -- Infor-
                  mation technology -- Universal Multiple-Octet Coded
                  Character Set (UCS) -- Part 1: Architecture and Basic
                  Multilingual Plane.

   [NICOL]        G.T. Nicol, "The Multilingual World Wide Web", Elec-
                  tronic Book Technologies, 1995,

   [NICOL2]       G.T. Nicol, "MIME Header Supplemented File Type", Work
                  in progress, <draft-nicol-mime-header-type-00.txt>,
                  EBT, October 1995.

   [RFC1345]      K. Simonsen, "Character Mnemonics & Character Sets",
                  RFC 1345, Rationel Almen Planlaegning, June 1992.

   [RFC1468]      J. Murai, M. Crispin and E. van der Poel, "Japanese
                  Character Encoding for Internet Messages", RFC 1468,
                  Keio University, Panda Programming, June 1993.

   [RFC1521]      N. Borenstein and N. Freed, "MIME (Multipurpose Inter-
                  net Mail Extensions) Part One: Mechanisms for Specify-
                  ing and Describing the Format of Internet Message Bod-
                  ies", RFC 1521, Bellcore, Innosoft, September 1993.

   [RFC1641]      D. Goldsmith, M.Davis, "Using Unicode with MIME", RFC
                  1641, Taligent inc., July 1994.

   [RFC1642]      D. Goldsmith, M. Davis, "UTF-7: A Mail-safe Transfor-
                  mation Format of Unicode", RFC 1642, Taligent inc.,
                  July 1994.

   [RFC1738]      T. Berners-Lee, L. Masinter, and M. McCahill, "Uniform
                  Resource Locators (URL)", RFC 1738, CERN, Xerox PARC,
                  University of Minnesota, October 1994.

   [RFC1766]      H. Alverstrand, "Tags for the Identification of Lan-
                  guages", RFC 1766, UNINETT, March 1995.

   [RFC1866]      T. Berners-Lee and D. Connolly, "Hypertext Markup Lan-
                  guage - 2.0", RFC 1866, MIT/W3C, November 1995.

   [RFC1867]      E. Nebel and L. Masinter, "Form-based File Upload in
                  HTML", RFC 1867, Xerox Corporation, November 1995.

   [RFC1942]      D. Raggett, "HTML Tables", RFC 1942, W3C, May 1996.

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   [RFC1945]      T. Berners-Lee, R.T. Fielding, and H. Frystyk Nielsen,
                  "Hypertext Transfer Protocol -- HTTP/1.0", RFC 1945,
                  MIT/LCS, UC Irvine, May 1996.

   [SQ91]         SoftQuad, "The SGML Primer", 3rd ed., SoftQuad Inc.,

   [TAKADA]       Toshihiro Takada, "Multilingual Information Exchange
                  through the World-Wide Web", Computer Networks and
                  ISDN Systems, Vol. 27, No. 2, Nov. 1994 , p. 235-241.

   [TEI]          TEI Guidelines for Electronic Text Encoding and Inter-
                  change.  <http://etext.virgina.edu/TEI.html>

   [UNICODE]      The Unicode Consortium, "The Unicode Standard --
                  Worldwide Character Encoding -- Version 1.0", Addison-
                  Wesley, Volume 1, 1991, Volume 2, 1992, and Technical
                  Report #4, 1993.  The BIDI algorithm is in appendix A
                  of volume 1, with corrections in appendix D of volume

   [UTF-8]        ISO/IEC 10646-1:1993 AMENDMENT 2 (1996). UCS Transfor-
                  mation Format 8 (UTF-8).

   [VANH90]       E. van Hervijnen, "Practical SGML", Kluwer Academicq
                  Publishers Group, Norwell and Dordrecht, 1990.

Authors' Addresses

   François Yergeau
   Alis Technologies
   100, boul. Alexis-Nihon, bureau 600
   Montréal  QC  H4M 2P2

   Tel: +1 (514) 747-2547
   Fax: +1 (514) 747-2561
   EMail: fyergeau@alis.com

   Gavin Thomas Nicol
   Electronic Book Technologies, Japan
   1-29-9 Tsurumaki,

   Tel: +81-3-3230-8161

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   Fax: +81-3-3230-8163
   EMail: gtn@ebt.com, gtn@twics.co.jp

   Glenn Adams
   118 Magazine Street
   Cambridge, MA 02139

   Tel: +1 (617) 864-5524
   Fax: +1 (617) 864-4965
   EMail: glenn@spyglass.com

   Martin J. Duerst
   Department of Computer Science
   University of Zurich
   Winterthurerstrasse 190
   CH-8057 Zurich

   Tel: +41 1 257 43 16
   Fax: +41 1 363 00 35
   E-mail: mduerst@ifi.unizh.ch

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