The "font" Top-Level Media Type
RFC 8081

Document Type RFC - Proposed Standard (February 2017; No errata)
Last updated 2017-02-28
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Internet Engineering Task Force (IETF)                         C. Lilley
Request for Comments: 8081                                           W3C
Category: Standards Track                                  February 2017
ISSN: 2070-1721

                    The "font" Top-Level Media Type

Abstract

   This memo serves to register and document the "font" top-level media
   type, under which subtypes for representation formats for fonts may
   be registered.  This document also serves as a registration
   application for a set of intended subtypes, which are representative
   of some existing subtypes already in use, and currently registered
   under the "application" tree by their separate registrations.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc8081.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Lilley                       Standards Track                    [Page 1]
RFC 8081                The 'font' Top-Level Type          February 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Background and Justification  . . . . . . . . . . . . . . . .   3
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Definition and Encoding . . . . . . . . . . . . . . . . .   5
     4.2.  Fragment Identifiers for Font Collections . . . . . . . .   5
     4.3.  Registration Procedure  . . . . . . . . . . . . . . . . .   6
     4.4.  Subtype Registrations . . . . . . . . . . . . . . . . . .   6
       4.4.1.  Generic SFNT Font Type  . . . . . . . . . . . . . . .   6
       4.4.2.  TTF Font Type . . . . . . . . . . . . . . . . . . . .   9
       4.4.3.  OpenType Layout (OTF) Font Type . . . . . . . . . . .  10
       4.4.4.  Collection Font Type  . . . . . . . . . . . . . . . .  12
       4.4.5.  WOFF 1.0  . . . . . . . . . . . . . . . . . . . . . .  14
       4.4.6.  WOFF 2.0  . . . . . . . . . . . . . . . . . . . . . .  15
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .  16
     5.2.  Informative References  . . . . . . . . . . . . . . . . .  17
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

   The process of setting type in computer systems and other forms of
   text presentation systems uses fonts in order to provide visual
   representations of the glyphs.  Just as with images, for example,
   there are a number of ways to represent the visual information of the
   glyphs.  Early font formats often used bitmaps, as these could have
   been carefully tuned for maximum readability at a given size on low-
   resolution displays.  More recently, scalable vector outline fonts
   have come into widespread use.  In these fonts, the outlines of the
   glyphs are described, and the presentation system renders the outline
   in the desired position and size.

   Over time, a number of standard formats for recording font
   descriptions have evolved.  Internet Media Types [RFC6838] are used
   to label content carried over Internet protocols.  This document
   defines a new top-level type "font" according to Section 4.2.7 of
   [RFC6838].  This top-level type indicates that the content specifies
   font data.  Under this top-level type, different representation
   formats of fonts may be registered.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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