ISO/IEC 14496-22:2019

Information technology — Coding of audio-visual objects — Part 22: Open Font Format

This document specifies the Open Font Format (OFF) specification, including the TrueType and Compact Font Format (CFF) outline formats. Many references to both TrueType and PostScript exist throughout this document, as Open Font Format fonts combine the two technologies. The document defines data structures for variaous font tables, and provides the necessary details for developers to build a font rendering and taxt layout/shaping engines in compliance with this document.

Technologies de l'information — Codage des objets audiovisuels — Partie 22: Format de police de caractères ouvert

General Information

• Status: Published
• Publication Date: 23-Jan-2019
• ICS: 35.040.40 - Coding of audio, video, multimedia and hypermedia information
• Technical Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Drafting Committee: ISO/IEC JTC 1/SC 29 - Coding of audio, picture, multimedia and hypermedia information
• Current Stage: 9092 - International Standard to be revised
• Start Date: 11-Aug-2023
• Completion Date: 11-Aug-2023

Relations

• Amended By: ISO/IEC 14496-22:2019/Amd 2:2023 - Information technology — Coding of audio-visual objects — Part 22: Open Font Format — Amendment 2: Extending colour font functionality and other updates
• Effective Date: 18-Dec-2021
• Amended By: ISO/IEC 14496-22:2019/Amd 1:2020 - Information technology — Coding of audio-visual objects — Part 22: Open Font Format — Amendment 1: Color font technology and other updates
• Effective Date: 31-Jul-2021
• Revises: ISO/IEC 14496-22:2015 - Information technology — Coding of audio-visual objects — Part 22: Open Font Format
• Effective Date: 09-Sep-2017
• Revises: ISO/IEC 14496-22:2015/Amd 2:2017 - Information technology — Coding of audio-visual objects — Part 22: Open Font Format — Amendment 2: Updated text layout features and implementations
• Effective Date: 09-Sep-2017
• Revises: ISO/IEC 14496-22:2015/Amd 1:2017 - Information technology — Coding of audio-visual objects — Part 22: Open Font Format — Amendment 1: Updates for font collections functionality
• Effective Date: 09-Sep-2017

Standards Content (Sample)

INTERNATIONAL ISO/IEC
STANDARD 14496-22
Fourth edition
2019-01
Information technology — Coding of
audio-visual objects —
Part 22:
Open Font Format
Technologies de l'information — Codage des objets audiovisuels —
Partie 22: Format de police de caractères ouvert
Reference number
©
ISO/IEC 2019
© ISO/IEC 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2019 – All rights reserved

Contents Page
Foreword . vii
Introduction . viii
1  Scope . 1
2  Normative references . 1
3  Terms, definitions and abbreviated terms . 1
3.1  Terms and definitions . 1
3.2  Abbreviated terms . 2
4  The Open Font file format . 3
4.1  Description . 3
4.2  Filenames . 3
4.3  Data types . 3
4.4  Table version numbers . 4
4.5  Top-level OFF organization . 5
4.5.1  Offset table . 5
4.5.2  Table directory . 5
4.5.3  Calculating checksums . 6
4.6  Font collections . 6
4.6.1  The Font Collection overview . 6
4.6.2  The Font Collection file structure . 7
4.6.3  TTC header . 7
5  Open font tables . 8
5.1  General . 8
5.2  Required common tables . 8
5.2.1  List of required tables . 8
5.2.2  cmap – Character to glyph index mapping table . 9
5.2.3  head – Font header . 21
5.2.4  hhea – Horizontal header . 23
5.2.5  hmtx – Horizontal metrics . 24
5.2.6  maxp – Maximum profile . 25
5.2.7  name – Naming table . 26
5.2.8  OS/2 – Global font information table . 45
5.2.9  Font class parameters . 67
5.2.10  post – PostScript . 67
5.3  Tables related to TrueType outlines . 69
5.3.1  List of TrueType outlines tables . 69
5.3.2  cvt – Control value table . 69
5.3.3  fpgm – Font program . 69
5.3.4  glyf – Glyf data . 70
5.3.5  loca – Index to location . 75
5.3.6  prep – Control value program . 75
5.3.7  gasp – Grid-fitting and scan-conversion procedure table . 76
5.4  Tables related to CFF outlines . 78
5.4.1  List of CFF outline tables. 78
5.4.2  CFF – Compact Font Format (version 1) table . 78
5.4.3  CFF2 – Compact Font Format (version 2) table . 78
5.4.4  VORG – Vertical origin table . 88
5.5  Table for SVG glyph outlines . 89
5.5.1  SVG – The SVG (Scalable Vector Graphics) table . 89
5.5.2  Color Palettes . 90
5.5.3  Glyph Identifiers . 91
5.5.4  Glyph Semantics and Metrics . 91
5.5.5  Glyph Rendering . 91
5.5.6  SVG glyph examples . 93
© ISO/IEC 2019 – All rights reserved iii

5.6  Tables related to bitmap glyphs .98
5.6.1  List of bitmap glyph tables .98
5.6.2  EBDT – Embedded bitmap data table .98
5.6.3  EBLC – Embedded bitmap location table . 101
5.6.4  EBSC – Embedded bitmap scaling table . 108
5.6.5  CBDT – Color bitmap data table . 109
5.6.6  CBLC – Color bitmap location table . 111
5.6.7  sbix – Standard bitmap graphics table . 112
5.7  Optional tables . 114
5.7.1  DSIG – Digital signature table . 115
5.7.2  hdmx – Horizontal device metrics . 117
5.7.3  kern – Kerning . 118
5.7.4  LTSH – Linear threshold . 120
5.7.5  MERG – Merge table . 121
5.7.6  meta – Metadata table . 125
5.7.7  PCLT – PCL 5 table . 128
5.7.8  VDMX – Vertical device metrics . 135
5.7.9  vhea – Vertical header table . 137
5.7.10  vmtx – Vertical metric table . 141
5.7.11  COLR – Color Table . 143
5.7.12  CPAL – Palette Table . 144
6  Advanced Open Font layout tables . 147
6.1  Advanced Open Font layout extensions . 147
6.1.1  Overview of advanced typographic layout extensions . 147
6.1.2  TrueType versus OFF layout . 149
6.1.3  OFF layout terminology . 149
6.1.4  Text processing with OFF layout . 151
6.1.5  OFF layout and Font variations . 153
6.2  OFF layout common table formats . 153
6.2.1  Overview . 153
6.2.2  OFF layout and Font variations . 154
6.2.3  Table organization . 155
6.2.4  Scripts and languages . 156
6.2.5  Features and lookups . 159
6.2.6  Coverage table . 162
6.2.7  Class definition table . 164
6.2.8  Device and VariationIndex tables . 165
6.2.9  Feature variations .
...

INTERNATIONAL ISO/IEC
STANDARD 14496-22
Fourth edition
2019-01
Information technology — Coding of
audio-visual objects —
Part 22:
Open Font Format
Technologies de l'information — Codage des objets audiovisuels —
Partie 22: Format de police de caractères ouvert
Reference number
©
ISO/IEC 2019
© ISO/IEC 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO/IEC 2019 – All rights reserved

Contents Page
Foreword . vii
Introduction . viii
1  Scope . 1
2  Normative references . 1
3  Terms, definitions and abbreviated terms . 1
3.1  Terms and definitions . 1
3.2  Abbreviated terms . 2
4  The Open Font file format . 3
4.1  Description . 3
4.2  Filenames . 3
4.3  Data types . 3
4.4  Table version numbers . 4
4.5  Top-level OFF organization . 5
4.5.1  Offset table . 5
4.5.2  Table directory . 5
4.5.3  Calculating checksums . 6
4.6  Font collections . 6
4.6.1  The Font Collection overview . 6
4.6.2  The Font Collection file structure . 7
4.6.3  TTC header . 7
5  Open font tables . 8
5.1  General . 8
5.2  Required common tables . 8
5.2.1  List of required tables . 8
5.2.2  cmap – Character to glyph index mapping table . 9
5.2.3  head – Font header . 21
5.2.4  hhea – Horizontal header . 23
5.2.5  hmtx – Horizontal metrics . 24
5.2.6  maxp – Maximum profile . 25
5.2.7  name – Naming table . 26
5.2.8  OS/2 – Global font information table . 45
5.2.9  Font class parameters . 67
5.2.10  post – PostScript . 67
5.3  Tables related to TrueType outlines . 69
5.3.1  List of TrueType outlines tables . 69
5.3.2  cvt – Control value table . 69
5.3.3  fpgm – Font program . 69
5.3.4  glyf – Glyf data . 70
5.3.5  loca – Index to location . 75
5.3.6  prep – Control value program . 75
5.3.7  gasp – Grid-fitting and scan-conversion procedure table . 76
5.4  Tables related to CFF outlines . 78
5.4.1  List of CFF outline tables. 78
5.4.2  CFF – Compact Font Format (version 1) table . 78
5.4.3  CFF2 – Compact Font Format (version 2) table . 78
5.4.4  VORG – Vertical origin table . 88
5.5  Table for SVG glyph outlines . 89
5.5.1  SVG – The SVG (Scalable Vector Graphics) table . 89
5.5.2  Color Palettes . 90
5.5.3  Glyph Identifiers . 91
5.5.4  Glyph Semantics and Metrics . 91
5.5.5  Glyph Rendering . 91
5.5.6  SVG glyph examples . 93
© ISO/IEC 2019 – All rights reserved iii

5.6  Tables related to bitmap glyphs .98
5.6.1  List of bitmap glyph tables .98
5.6.2  EBDT – Embedded bitmap data table .98
5.6.3  EBLC – Embedded bitmap location table . 101
5.6.4  EBSC – Embedded bitmap scaling table . 108
5.6.5  CBDT – Color bitmap data table . 109
5.6.6  CBLC – Color bitmap location table . 111
5.6.7  sbix – Standard bitmap graphics table . 112
5.7  Optional tables . 114
5.7.1  DSIG – Digital signature table . 115
5.7.2  hdmx – Horizontal device metrics . 117
5.7.3  kern – Kerning . 118
5.7.4  LTSH – Linear threshold . 120
5.7.5  MERG – Merge table . 121
5.7.6  meta – Metadata table . 125
5.7.7  PCLT – PCL 5 table . 128
5.7.8  VDMX – Vertical device metrics . 135
5.7.9  vhea – Vertical header table . 137
5.7.10  vmtx – Vertical metric table . 141
5.7.11  COLR – Color Table . 143
5.7.12  CPAL – Palette Table . 144
6  Advanced Open Font layout tables . 147
6.1  Advanced Open Font layout extensions . 147
6.1.1  Overview of advanced typographic layout extensions . 147
6.1.2  TrueType versus OFF layout . 149
6.1.3  OFF layout terminology . 149
6.1.4  Text processing with OFF layout . 151
6.1.5  OFF layout and Font variations . 153
6.2  OFF layout common table formats . 153
6.2.1  Overview . 153
6.2.2  OFF layout and Font variations . 154
6.2.3  Table organization . 155
6.2.4  Scripts and languages . 156
6.2.5  Features and lookups . 159
6.2.6  Coverage table . 162
6.2.7  Class definition table . 164
6.2.8  Device and VariationIndex tables . 165
6.2.9  Feature variations .
...