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Versions: 00 01                                                         
INTERNET-DRAFT                                                  C. Apple
<draft-ietf-schema-proc-list-01.txt>                           AT&T Labs
Expires: October 21, 1998                                    M. Mealling
                                                 Network Solutions, Inc.
                                                           21 April 1998




                  Directory Schema Listing Procedures
                  <draft-ietf-schema-proc-list-01.txt>

Status of this Memo

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

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time. It is inappropriate to use Internet- Drafts as reference
   material or to cite them other than as ``work in progress.''

   To learn the current status of any Internet-Draft, please check the
   ``1id-abstracts.txt'' listing contained in the Internet- Drafts
   Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
   munnari.oz.au (Pacific Rim), or ftp.isi.edu (US West Coast).

Abstract

   This memo documents procedures for listing directory service schemas
   in a centrally operated, administered, and maintained repository.
   This repository will be available as a resource to directory protocol
   and service implementors to facilitate schema discovery.
















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                             Table of Contents

   1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . .  3
   1.1 Terms and Definitions. . . . . . . . . . . . . . . . . . . .  3
   2.0 Directory Schema Listing . . . . . . . . . . . . . . . . . .  5
   2.1 Schema Listing Request Architecture Diagram. . . . . . . . .  5
   2.2 Listing Requirements . . . . . . . . . . . . . . . . . . . .  6
   2.2.1 Functionality Requirements . . . . . . . . . . . . . . . .  6
   2.2.2 Naming Requirements. . . . . . . . . . . . . . . . . . . .  6
   2.2.3 Content Formatting and Transfer Encoding Requirements. . .  6
   2.2.4 Security Requirements. . . . . . . . . . . . . . . . . . .  7
   2.2.5 Usage and Implementation Non-requirements. . . . . . . . .  8
   2.2.6 Publication Requirements . . . . . . . . . . . . . . . . .  8
   2.3 Listing Procedure. . . . . . . . . . . . . . . . . . . . . .  9
   2.3.1 Announcement and Community Review. . . . . . . . . . . . .  9
   2.3.2 Community Review and Assessment. . . . . . . . . . . . . . 10
   2.3.3 Primary Repository Operator Listing. . . . . . . . . . . . 10
   2.4 Comments on Schema Listings. . . . . . . . . . . . . . . . . 10
   2.5 Location of List of Available Schema . . . . . . . . . . . . 10
   2.6 Primary Repository Operator Procedures for Listing Schemas . 10
   2.7 Change Control . . . . . . . . . . . . . . . . . . . . . . . 12
   2.8 Listing Request Formats. . . . . . . . . . . . . . . . . . . 13
   2.8.1 Schema Unit Listing Request Format . . . . . . . . . . . . 13
   2.8.2 Schema Pak Listing Request Format. . . . . . . . . . . . . 14
   2.9 Primary Repository Operator Responsibilities and Constraints 14
   3.0 Security Considerations. . . . . . . . . . . . . . . . . . . 14
   4.0 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
   5.0 References . . . . . . . . . . . . . . . . . . . . . . . . . 15
   6.0 Authors' Address . . . . . . . . . . . . . . . . . . . . . . 16






















Apple, Mealling                                                 [Page 2]


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1.0 Introduction

   There is a growing number of places where schema for Internet
   Directory Services are being defined, with varying degrees of
   documentation.  This plethora of schemas is unavoidable in the light
   of the needs of different service communities, but it makes it
   difficult for directory service builders to find and make use of an
   existing schema that will serve their needs and increase
   interoperability with other systems. A listing service providing a
   single point of discovery for directory service schema will promote
   schema reuse, reduce duplication of effort, and thus promote
   directory service interoperability. Listed schema will be assiged a
   permanent, unique listing listing name as a part of the creating
   schema listing requests; which starts the schema listing process.
   This listing process was defined to ensure that directory service
   schema writers can publish their schema in a public forum so that
   they will be re-used.

   The IETF schema listing service has public read access and
   restricted, moderated write access. Currently, this listing service
   is centrally operated, administered, and maintained by the Internet
   Directory Consortium.  The schema listing repository is mirrored to
   ensure some level of redundancy for read access.

   This document defines schema listing procedures which use the
   Internet Directory Consortium as the primary listing repository
   operator.

1.1 Terms and Definitions

   Information Object - a descriptive abstraction of some real-world
   object

   Object Attribute - a descriptive property of an information object;
   typically, object attributes are defined in terms of semantic and
   syntactic definitions

   Schema - a collection of definitions for related information objects

   Schema Unit - a related or grouped set of object attributes that form
   a discrete unit within the context of a schema for a particular
   protocol; examples include an LDAP object class or a WHOIS++ template

   Schema Pak - a related or grouped set of schema units that
   collectively specify a schema associated with a particular protocol;
   an example of a schema pak is the set of LDAP object classes
   specified in [RFC2256]




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   Metadata - characteristics that differentiate one schema unit or
   schema pak from another; used to catalog listing service content;
   structured using a profile of [MIMEDIR]; also contains references to
   files stored within and outside of a listing repository

   Schema Unit Content - a formal specification of a schema unit using a
   profile of [MIMEDIR]

   Schema Unit Listing - the combination of a single schema unit content
   file intended for use within the context of a particular protocol and
   a file containing metadata describing the schema unit specified
   within that schema unit content file

   Schema Pak Listing - a single metadata file containing information
   describing and referring to a set of related or grouped schema unit
   content files

   Repository - a database in which listings are stored

   Listing Request - a proposed schema unit listing or schema pak
   listing formatted using [MIME] constructs that is submitted for
   consideration as a listing to be published in a repository

   Operator - an organization that administers and maintains a
   repository

   Primary Repository - the repository that masters the schema listings
   database

   Shadow Repository - a repository that mirrors the primary repository

   Contact Person - the name of the individual who holds the authority
   to update a listing and who should be contacted if questions or
   concerns arise related to a listing or listing request

   Listing Authority Contact - the name of the individual who holds
   authority to replace a contact person; can be either the contact
   person for a listing or an alternate contact within the organization
   to which the contact person belongs (this allows one person
   organizations to list schema)

   The terms for specifying requirement level defined in [RFC2119] are
   used in this document.








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2.0 Directory Schema Listing

2.1 Schema Listing Request Architecture Diagram


                      Schema Writer
                            |  <-----------------schema listing request with
                            |                    a permanent, unique listing
                            |                    name obtained from the primary
                            V                    repository operator
            Schema Listing Request Review List
                            |
                            V
                +-----------------------+
                |Significant objections | YES
                |raised within 2 weeks? |----> Back to the drawing board....
                +-----------------------+
                            | NO (List Moderator recommends that listing
           Schema Listing-->|     be published subject to comments on list.)
               Request      V
                   +-----------------+
                   |Request meets    | NO
                   |all requirements?| ----> Back to the drawing board....
                   +-----------------+
                            | YES
                            |  <-----------------metadata/listing content
                            V
                  Repository Mirroring Agent
                   |        |    ...      |
                   V        V             V
           +----------+ +----------+ +----------+
           |Repository| |Repository| |Repository| where: 1 is the primary
           |    1     | |    2     | |    n     |        2..n are replicas
           +----------+ +----------+ +----------+


   Listing of a new schema starts with the construction of a listing
   request. Schema writers obtain a unique listing name and include it
   in the schema listing request sent to a moderated request review
   list.  Following a comment period of 2 weeks, if no significant
   objections are raised (determined by the moderator), the moderator
   sends the listing request to the primary listing repository operator,
   subject to incorporation of relevant comments by the schema writer.
   Listing requests are checked to verify compliance with the
   requirements and conditions discussed below and the listing will be
   published in the primary listing repository if appropriate. A
   mirroring agent replicates the new listing across the primary and
   mirrored copies of the listing repository database.



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   The following sections describe the requirements and procedure.

2.2 Listing Requirements

   Listing requests are all expected to conform to various requirements
   laid out in the following sections.

2.2.1 Functionality Requirements

   Schema unit listings MUST include two different types of information:

      (1) metadata

      (2) schema unit content

   Metadata will be used to catalog repository files by characteristics
   that differentiate listings.

   Schema unit content MUST be limited to the specification of a single
   schema unit.

2.2.2 Naming Requirements

   All listings MUST have a valid OID as their name.

   The primary listing repository operator MUST provide schema writers
   with the following components of a listing request name:

     + a sequence number assigned to each listing
       by the primary repository operator

     + a version number assigned to each listing
       version by the primary repository operator

2.2.3 Content Formatting and Transfer Encoding Requirements

   All listings MUST employ a common data format.

   Metadata and schema unit content format and transfer encoding MUST
   utilize appropriate [MIMEDIR] profiles.

   Currently, five [MIMEDIR] profiles have been defined for use in the
   schema listing service:

      [MIMELDAP] MUST be used to format and encode LDAPv3 schema unit
      content.

      [MIMEWHOISPP] MUST be used to format and encode WHOIS++ schema



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      unit content.

      [MIMEWHOIS] MUST be used to format and encode WHOIS schema unit
      content.

      [MIMERWHOIS] MUST be used to format and encode RWHOIS schema unit
      content.

      [METASYN] MUST be used to format and encode metadata for all
      schema unit listings, schema pak listings, and listing requests.

   Other [MIMEDIR] profiles MAY be defined for use in the schema listing
   service; this procedures document will be updated reflect such
   changes.

2.2.4 Security Requirements

   An analysis of security issues for listed schema SHOULD be performed
   prior to submitting a listing request. However, regardless of what
   security analysis has or has not been done, all descriptions of
   security issues MUST be as accurate as possible. In particular, a
   statement that there are "no security issues associated with this
   type" MUST not be confused with "the security issues associates with
   this type have not been assessed".

   There is absolutely NO REQUIREMENT that listed schema be secure or
   completely free from risks.  Nevertheless, all known security risks
   SHOULD be identified in the listing request.

   The security considerations section of all requests is subject to
   continuing evaluation and modification, and in particular MAY be
   extended by use of the "comments on schema listings" mechanism
   described in subsequent sections.

   Some of the issues that SHOULD be looked at in a security analysis of
   a schema listing are:

      (1) A listing might include specifications mandating
          exposure of certain attributes which would result in
          compromising the privacy of an organization or
          individual.

      (2) A listing might be intended for use by
          applications requiring some sort of security
          assurances not provided by the schema specified
          in the schema unit content or in the schema unit
          content files referenced in a schema pak listing.




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2.2.5 Usage and Implementation Non-requirements

   In the directory services environment, where information on the
   embedded schema knowledge of a directory client is frequently not
   available to a server, maximum interoperability is attained by
   restricting the schema used to those agreed upon by the large
   community of directory service technology developers and users. This
   was asserted in the past as a reason to limit the number of possible
   schema to one via standards processes and resulted in a change
   process with a significant hurdle and delay for those seeking to
   modify and extend standard schema to better suite their needs.
   Eventually, various individuals and organizations began using non-
   standard schema, making interoperability difficult to achieve.

   The need for "common" or "meta" schema listings does not require
   limiting the publication of new listings. If a set of schema unit
   listings is recommended for a particular application, that should be
   asserted by an intended use statement specific for that application
   and/or environment withing a schema pak listing metadata file. If a
   set of schema pak listings is recommended for a particular
   application, that should be asserted by a separate intended use
   statement specific for the application and/or environment; or an
   additional schema pak listing containing references to all of the
   relevant schema unit listings should be created, reviewed, and
   published.

   As such, universal support and implementation of a schema is NOT a
   requirement for listing it.  If, however, a schema is explicitly
   intended for limited use, this should be noted in its listing(s).

2.2.6 Publication Requirements

   Requests for schema listed in the IETF schema listing service MAY be
   published as RFCs. The primary listing repository operator will
   retain copies of all schema listing requests that meet the
   requirements specified below and "publish" them as part of the schema
   listing repository.

   The listing of a schema does not imply endorsement, approval, or
   recommendation by the IETF or even certification that the
   specification is adequate for the intended use of the schema. To
   become Internet Standards, protocol, data objects, or whatever must
   go through the IETF standards process. This is too difficult and too
   lengthy a process for the convenient listing of schema.

   It is expected that applicability statements for particular
   applications will be published from time to time that recommend
   implementation of, and support for, schema that have proven



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   particularly useful in those contexts.

2.3 Listing Procedure

   The following procedure has been implemented by the primary listing
   repository operator for review and approval of new listings. This is
   not a formal standards process, but rather an administrative
   procedure intended to foster re-use of directory services schema and
   to provide a method for collecting schema in a publicly accessible
   repository.

   Submitting listing requests can be done via mail, treating posting of
   a formatted request containing the specification of schema unit
   content for a particular protocol and/or metadata to the mailing list

      ietf-schema-review@pilot.schema.dir.reg.int

   as a first step.

2.3.1 Announcement and Community Review

   While listed schema are NOT REQUIRED to be published as RFCs, listing
   requests documenting them MUST be posted to the mailing list

      ietf-schema-review@pilot.schema.dir.reg.int,

   allowing a review and comment period of at least 2 weeks. This is
   necessary to prevent the malicious as well as unintended introduction
   of obviously bogus or frivolous schema into the listing repository.

   Schema writers wishing to have their schema listed by the primary
   listing repository operator, MUST specify any such schema (may
   require the creation/submission of more than one request) according
   to one of the following [MIMEDIR] profiles: [MIMELDAP],
   [MIMEWHOISPP], [MIMEWHOIS], or [MIMERWHOIS].  Other such profiles may
   be defined elsewhere and this procedures document will be update to
   reflect such process changes.

   Metadata, as specified in [METASYN], MUST also be included in this
   request.  A template for listing requests is specified in paragraph
   2.8.  Schema writers MUST use this template.

   Schema writers MUST also construct a unique listing request name for
   each request being created. Listing names are constructed according
   to the type valuetype syntax and type special notes for the
   'listingName' MIME Directory Type [METASYN].

   Once created, the listing request should be sent to ietf-schema-



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   review@pilot.schema.dir.reg.int.

2.3.2 Community Review and Assessment

   Moderated discussions on the ietf-schema-
   review@pilot.schema.dir.reg.int mailing list will enable a means of
   gauging concensus as to whether or not the schema being proposed is
   bogus. If there is no significant reason to believe that a schema is
   useful or if it appears to be a bogus or malicious request, the
   moderator will not submit a listing request to the primary listing
   repository operator; otherwise, they may do so.

2.3.3 Primary Repository Operator Listing

   Provided that the schema listing request meets the requirements
   defined in paragraph 2.1, the ietf-schema-
   review@pilot.schema.dir.reg.int list moderator will send that listing
   request to the primary repository operator, which will check this
   listing request for validity, and make the listing available to the
   community.

2.4 Comments on Schema Listings

   Comments on listings may be submitted by members of the IETF
   community to for consideration by the rest of the community and the
   primary listing repository operator. These comments will be passed on
   to the contact person for the listing if possible.  Submitters of
   comments may request that their comment be attached to the listing
   itself. If the ietf-schema-review@pilot.schema.dir.reg.int list
   moderator is able to gauge concensus affirming the inclusion of such
   a comment, it will be made accessible in conjunction with the listing
   itself.

2.5 Location of List of Available Schema

   Listings will be posted in the anonymous FTP directory
   "ftp://www.pilot.schema.dir.reg.int/schema/" and all listings will be
   summarized in a periodically issued RFC. Schema unit content, schema
   pak listings, and/or other supporting material may also be published
   as an Informational RFC by sending it to "rfc-editor@isi.edu" (please
   follow the instructions to RFC authors [RFC2223]).

2.6 Primary Repository Operator Procedures for Listing Schemas

   Listings will be published by the primary repository operator
   automatically and without any formal review as long as the following
   minimal conditions are met:




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      (1) All listings MUST have a valid OID as their name.

      (2) All schema unit listing requests MUST include both
          metadata and schema unit content.

      (3) All schema pak listing requests MUST be limited to
          metadata.

      (4) Metadata MUST comply with [METASYN].

      (5) Schema unit content MUST be compliant with at one
          of the following [MIMEDIR] profiles:

             + [MIMELDAP] (for LDAPv3 schema specifications)
             + [MIMEWHOISPP] (for WHOIS++ schema specifications)
             + [MIMEWHOIS] (for WHOIS schema specifications)
             + [MIMERWHOIS] (for RWHOIS schema specifications)

          Other [MIMEDIR] profiles may be defined in the future and this
          document will be updated to reflect such additional profiles.

      (6) Any security considerations given must not be obviously
          bogus. It is neither possible nor necessary for the
          primary listing repository operator to conduct a
          comprehensive security review of listings.
          However, the listing request review committee
          (the members of the listing request review
          mailing list) has the authority and expertise
          to identify obviously incompetent material
          and exclude it.

      (7) Schema listing requests MAY be signed using PGP/MIME
          as described in [RFC2015]. The primary listing repository
          operator MUST be able to accept listing requests
          in PGP/MIME messages, although they are NOT REQUIRED
          to validate or retain the signatures.

      (8) Listing request MUST be formatted according to
          paragraph 2.8.

      (9) If a listing request includes one or more
          URI-based references to information that would not be
          included in a resulting listing, but is associated with
          the schema or schema unit specified by the request,
          a fingerprint of this information MUST be included with
          each such reference as specified in [METASYN]. The schema
          writer MUST also include a special caveat metadata element
          (as specified in [METASYN]) if at least one such



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          reference is included in the request.

2.7 Change Control

   Once a listing has been published by the primary repository operator,
   the contact person may request a change to its definition. The
   contact person for a listed schema is defined to be the person or
   organizational role or entity who submitted the original listing
   request.

   The change request follows the same procedure as the listing request

      (1) Publish the revised listing request on the
          ietf-schema-review@pilot.schema.dir.reg.int list.

      (2) Leave at least two weeks for comments.

      (3) Publish using the primary listing repository
          operator after formal review if required.

   Changes MAY be requested when there are serious omissions or errors
   in the published listing or when other factors which would justify a
   change request, such as an emerging need of the user community for a
   listed schema which cannot be addressed by that listed schema in its
   present form. When review is required, a change request MAY be denied
   if it renders entities that were valid under the previous definition
   invalid under the new definition.

   The primary listing repository provider SHOULD attempt to verify the
   authority of a person claiming to be the contact for a listing, prior
   to implementing such changes.

   The contact person for a listing MAY pass responsibility for that
   listing to another person or agency by informing the primary listing
   repository operator and the ietf-schema-
   announce@pilot.schema.dir.reg.int list; this can be done without
   discussion or review.

   The IESG may reassign responsibility for a listing. The most common
   case of this will be to enable changes to be made to types where the
   contact person for the listing has died, moved out of contact, or is
   otherwise unable to make changes that are important to the community.

   Listings will not be deleted; listings which are no longer believed
   appropriate for use can be declared OBSOLETE by a change to their
   "intended use" field; such listings will be clearly marked in
   repository content summary RFCs published by the primary listing
   repository operator.



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2.8 Listing Request Formats

2.8.1 Schema Unit Listing Request Format

   To: ietf-schema-review@pilot.schema.dir.reg.int
   Subject: schema unit listing request
   MIME-Version: 1.0
   Message-Id: <ids1@wherever.com>
   Content-Type: multipart/related; start=3@foo.com; boundary="boundary"
   Content-ID: top@foo.com

   --boundary
   Content-Type: text/directory;
                 profile="schema-metadata-0";
                 charset="utf-8"
   Content-Transfer-Encoding: Quoted-Printable
   Content-ID: 3@foo.com

   (metadata elements and values as specified in [METASYN] and embedded
   in a text/directory MIME component of profile "schema-meta-0")

   --boundary
   Content-Type: text/directory;
                 profile="<mimedir-profile-type>";
                 charset="utf-8"
   Content-Transfer-Encoding: Quoted-Printable
   Content-ID: 3@foo.com

   (a schema specification compliant with a profile of [MIMEDIR]
   corresponding to the value of <mimedir-profile-type>)

   --boundary

   Where:


           <mimedir-profile-type> = "schema-ldap-0" / "schema-whoispp-0" /
                                    "schema-whois-0" / "schema-rwhois-0"













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2.8.2 Schema Pak Listing Request Format

   To: ietf-schema-review@pilot.schema.dir.reg.int
   Subject: schema pak listing request
   MIME-Version: 1.0
   Message-Id: <ids1@wherever.com>
   Content-Type: text/directory;
                 profile="schema-metadata-0";
                 charset="utf-8"
   Content-Transfer-Encoding: Quoted-Printable

   (metadata elements and values as specified in [METASYN] and embedded
   in a text/directory MIME component of profile "schema-meta-0")

2.9 Primary Repository Operator Responsibilities and Constraints

   The data residing in the repository is not the property of the
   repository operator. Since the schema actually listed are the
   intellectual property of the entities creating the listing, the
   repository operator cannot claim them as intellectual property. All
   metadata surrounding the system is considered to be either in the
   public domain or is owned by the IANA (or some other suitable
   entity). The repository operator can make no claims whatsoever of
   ownership over any data in the repository.

   The repository operator can also make no determinations of
   appropriateness or suitability of a schema to be listed. This
   responsibility rests solely with the members of the listing request
   review committee (the members of the listing request review mailing
   list). If the list coordinator requests that the repository operator
   publish a schema listing, the repository operator MUST include the
   schema listing or be relieved of the reponsibility of running the
   repository.

   Currently, the ability to advertise products and services on the
   repository web site to recoup monies used in operating the service is
   allowed. At any time, the review committee make make a policy
   decision on the appropriateness of ads on the repository pages.

3.0 Security Considerations

   As described in [LISTRQMT], the subject of trust with respect to most
   aspects of the service involving the exchange of information
   (submitting a listing request, updating an existing listing, or
   retrieving a listing) is not addressed in this document. However, the
   primary schema listing repository operator will take reasonable steps
   to ensure that information associated with the service is as accurate
   and authentic as possible.



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   If users of the schema listing service obtain and use listings from
   the repository, they SHOULD verify that any fingerprints contained as
   a part of metadata for references to related content hosted outside
   of the repository are valid. This can be verified by computing the
   MD5 checksum [RFC1321] of the referenced content and comparing it
   with the fingerprint value. If this verification fails, the user of
   this schema information can assume that this external content has
   changed after the listing was published. In any case, no repository
   operator has control over external content referenced by URIs in the
   metadata. Thus the establishment of trust as it relates to the
   validity of fingerprints and the content which they represent is
   solely the user's responsibility and is OPTIONAL.

4.0 Acknowledgements

   The format and much of the content in this document is based on
   [RFC2048].

   The engineering team for listing service requirements:

      Chris Apple - AT&T Labs
      Michael Mealling - NSI
      Sanjay Jain - Oracle
      John Strassner - Cisco
      Sam Sun - CNRI
      Mark Wahl - Critical Angle
      Chris Weider - Microsoft

   Paul Hoffman for review and comments resulting from his effort to
   develop a platform for the initial release of the schema listing
   service.

5.0 References

   [FILESYN] C. Apple, "Directory Schema Listing File Name Syntax",
   INTERNET-DRAFT <draft-ietf-schema-file-list-01.txt>, April 1998.

   [LISTRQMT] C. Apple, "Requirements for the Initial Release of a
   Directory Schema Listing Service", INTERNET-DRAFT <draft-ietf-
   schema-rqmts-list-01.txt>, April 1998.

   [METASYN] C. Apple, "A MIME Directory Profile for Schema Listing Meta
   Data", INTERNET-DRAFT <draft-ietf-schema-mime-metadata-01.txt>, April
   1998.

   [MIMELDAP] M. Wahl, "A MIME Directory Profile for LDAP Schema",
   INTERNET-DRAFT <draft-ietf-schema-ldap-00.txt>, January 1998.




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   [MIMEWHOISPP] L. Daigle, "A MIME Directory Profile for Whois++
   Schema", INTERNET-DRAFT <draft-ietf-schema-whois++-00.txt>, April
   1998.

   [MIMEWHOIS] R. Moats, "A MIME Content-Type for WHOIS", INTERNET-DRAFT
   <draft-ietf-schema-whois-00.txt>, April 1998.

   [MIMERWHOIS] M. Mealling, "A MIME Directory Profile for RWhois 1.5
   Schema", INTERNET-DRAFT <draft-ietf-schema-rwhois-00.txt>, March
   1998.

   [RFC1321] R. Rivest, "The MD5 Message-Digest Algorithm", RFC 1321,
   April 1992.

   [RFC1630] T. Berners-Lee, "Universal Resource Identifiers in WWW",
   RFC 1630, June 1994.

   [RFC2015] M. Elkins, "MIME Security with Pretty Good Privacy (PGP)",
   RFC 2015, October 1996.

   [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
   Requirement Level", RFC 2119, March 1997.

   [RFC2048] N. Freed, J. Klensin, J. Postel, "Multipurpose Internet
   Mail Extensions (MIME) Part Four: Registration Procedures", RFC 2048,
   November 1997.

   [RFC2223] J. Postel, J. Reynolds, "Instructions to RFC Authors", RFC
   2223, October 1997.

6.0 Authors' Address

   Chris Apple
   Room 2F-165
   AT&T Labs
   600 Mountain Ave
   Murray Hill, NJ 07974
   US

   Phone: +1 908 582 2409
   Fax:   +1 908 582 3296
   Email: capple@att.com

   Michael Mealling
   505 Huntmar Park Drive
   Herndon, VA 22070
   US




Apple, Mealling                                                [Page 16]


INTERNET-DRAFT    Directory Schema Listing Procedures      21 April 1998


   Phone: +1 703 742 0400
   Fax: +1 703 742 9552
   Email: michaelm@rwhois.net


             This Internet-Draft expires on October 21, 1998.













































Apple, Mealling                                                [Page 17]