OpenType Specification Change Log (OpenType 1.9)

Version 1.9

Released December 2021

Structure names were revised in chapter2 and fvar chapters; see below for details.

Minor editorial changes (not detailed below) were made in the following chapters: chapter2, cmap, dvaraxisreg, featurelist, features_ae, glyf, gpos, gsub, gvar, hvar, index, kern, languagetags, name, otvarcommonformats, otvaroverview, prep, recom, tt_instructions, ttch01.

Summary of changes:

  • chapter2

    • Changed spellings of field names of ConditionFormat1 table.

  • cmap

    • For platform ID 0, encoding ID 3, removed suggestion of using format 0 subtable.
    • Clarified requirements for UVSes in a format 14 subtable and entries in other 'cmap' Unicode subtables.
    • Corrected description of the entrySelector field (post-release erratum).

  • colr

    • Added version 1 header and related structures.
    • Revised introductory sections and other editorial changes.
    • Added recommendation against using bold or italic simulations.
    • Corrected how angles are measured for PaintSweepGradient and PaintVarSweepGradient (post-release erratum).

  • cpal

    • Added reference to CSS Color Module Level 4.
    • Added section on interpolation of colors.

  • feature_ae

    • Modified 'cvXX' description.
    • Corrected use of non-preferred region / language / script names (post-release erratum).

  • feature_fj

    • Modified 'frac' feature description.

  • features_ko

    • Modified 'lfbd' feature description.

  • features_pt

    • Modified 'rtbd' feature description.

  • fvar

    • Changed record name “Tuple” to “UserTuple”.

  • glyf

    • Added remarks regarding glyph bounding rectangles in variable fonts.
    • Clarified interpretation of X_SHORT_VECTOR and Y_SHORT_VECTOR flags.
    • Clarified interpretation of the ARGS_ARE_XY_VALUES and ROUND_XY_TO_GRID component flags, and other aspects of composite glyph descriptions.
    • Changed FWord and F2Dot14 to FWORD and F2DOT14.

  • gpos

    • Clarified consistency requirement for extension subtables within a given Lookup table.

  • gsub

    • Clarified consistency requirement for extension subtables within a given Lookup table.
    • Corrected use of non-preferred region / language / script name (post-release erratum).

  • gvar

    • Corrected type in sharedTuples array to Tuple.
    • Corrected spelling of GlyphVariationData and TupleVariationHeader.

  • head

    • Clarified meaning of unitsPerEm, xMin, yMin, xMax and yMax values.
    • Added remarks regarding glyph bounding rectangles in variable fonts.

  • hvar

    • Moved description of the DeltaSetIndexMap to the OpenType Font Variations Common Table Formats chapter.

  • languagetags

    • Added information on how to request new language system tags.
    • Added 'MONT', 'TJL '.
    • Added 'INUK' (post-release update).
    • Corrected entries for 'TUL ', 'TUM ' (post-release erratum).
    • Corrected use of non-preferred region / language / script name (post-release erratum).

  • maxp

    • Added CFF2 as requiring version 0.5.

  • meta

    • Clarified that 'slng' value should be superset of 'dlng'.
    • Fixed URL for BCP 47 (post-release erratum).
    • Corrected use of non-preferred region / language / script names (post-release erratum).

  • name

    • Clarified encoding scheme for platform 0 strings.
    • Added note regarding platform 3 and non-conforming legacy CJK fonts.
    • Corrected use of non-preferred region / language / script name (post-release erratum).

  • os2

    • Include details for legacy calculation of xAvgCharWidth in OS/2 versions 0 to 2 that were omitted since version 1.8.3.
    • Corrected use of non-preferred region / language / script name (post-release erratum).

  • otff

    • Added Offset24 type.
    • Added clarifications regarding NULL subtable offsets.
    • Added recommendation against duplicate tables.

  • otvarcommonformats

    • Added COLR as a table using variation data.
    • Moved description of DeltaSetIndexMap from the HVAR chapter to this chapter. Sub-divided the entryFormat field into separate format and entryFormat fields, and added a format 1 DeltaSetIndexMap.
    • Described application of deltas to F2DOT14, Fixed.
    • Revised ItemVariationData subtable adding support for 32-bit deltas. Also changed field name “shortDeltaCount” to “wordDeltaCount”.

  • otvaroverview

    • Clarified that any aspect of appearance can vary in a variable font.
    • Added details regarding integer bit depth in the algorithm for interpolation of instance values.

  • post

    • Changed FWord to FWORD.

  • recom

    • Revised guidance for baseline-to-baseline distance.

  • scripttags

    • Added script tags for new scripts in Unicode 14.0.
    • Added remarks regarding 'jamo' and 'mymr'.
    • Corrected use of non-preferred region / language / script name (post-release erratum).

  • stat

    • Emphasized recommendation to include axis value tables covering all named instances of a variable font.

  • tt_graphics_state

    • Fix incorrect names of instructions and zone pointers.

  • tt_instructing_glyphs

    • Added clarification regarding unused distance type 3.

  • tt_instructions Clarified that FDEF and IDEF may not be invoked in glyph programs.

  • ttch01

    • Clarified when the interpreter stack is cleared.
    • Clarified where functions and instructions can or cannot be defined or redefined, and the persistence of definitions.
    • Clarified when the control value program is run and the relationship between the control value program, Control Value Table, and the 'cvt ' table.
    • Clarified interaction between the control value program and Graphics State variables.
    • Clarified interactions between zone 0 and the control value and glyph programs.
    • Clarified use of the storage area by font, control value and glyph programs.
    • Added section discussing persistence of storage or CVT values set in a glyph program and interaction with glyph caches.
    • Clarified control of the scan converter mode using SCANCTRL.

  • vvar

    • For description of the DeltaSetIndexMap, changed the cross-reference from the HVAR chapter to the OpenType Font Variations Common Table Formats chapter.

Version 1.8.4

Released November 2020

Names of tables, fields or flags in the following chapters were revised to conform to conventions used across this specification:

These name changes are enumerated in detail below.

References to “TrueType”, when this specification is intended, have been removed, changed to “OpenType”, or otherwise clarified in the following chapters: chapter2.htm, dsig.htm, hvar.htm, otff.htm, post.htm, recom.htm, ttch01.htm, vmtx.htm, vorg.htm.

Minor editorial changes (not detailed below) were made in the following chapters: avar.htm, base.htm, baselinetags.htm, cff.htm, cff2charstr.htm, chapter2.htm, cmap.htm, colr.htm, cpal.htm, dsig.htm, dvaraxistag_ital.htm, dvaraxistag_opsz.htm, dvaraxistag_slnt.htm, dvaraxistag_wdth.htm, dvaraxistag_wght.htm, eblc.htm, featurelist.htm, features_ae.htm, features_fj.htm, features_ko.htm, features_pt.htm, features_uz.htm, featuretags.htm, gdef.htm, gpos.htm, gsub.htm, gvar.htm, hdmx.htm, head.htm, hvar.htm, index.htm, languagetags.htm, ltsh.htm, math.htm, meta.htm, otff.htm, otvarcommonformats.htm, post.htm, scripttags.htm, stat.htm, svg.htm, tt_instructing_glyphs.htm, tt_instructions.htm, ttch01.htm, ttochap1.htm, ttoreg.htm, vhea.htm, vmtx.htm, vorg.htm, vvar.htm.

Summary of changes:

  • avar.htm

  • base.htm

    • Changed field names:
      • BaseValues table: “baseCoords” to “baseCoordOffsets”
      • MinMax and FeatMinMax tables: “minCoord” to “minCoordOffset”
      • MinMax and FeatMinMax tables: “maxCoord” to “maxCoordOffset”
      • BaseCoordFormat3: “deviceTable” to “deviceOffset”

  • cbdt.htm

    • Added descriptions of fields for BigGlyphMetrics, SmallGlyphMetrics.
    • Changed characterization of BitmapSize from table to record.

  • cblc.htm

    • Changed characterization of BitmapSize from table to record.
    • Revised description of CBLC header to incorporate BitmapSize records array.

  • cff2.htm

    • Added note to description of FDSelect Format 3 regarding the maximum glyph ID of 65534.

  • cffspec.htm

    • Page removed. (The page only provided an external link, already in cff.htm.)

  • chapter2.htm

    • Changed table name: “ConditionTableFormat1” to “ConditionFormat1” (table).
    • Changed field names:
      • Script table: “defaultLangSys” to “defaultLangSysOffset”
      • LangSys table: “lookupOrder” to “lookupOrderOffset”
      • Feature table: “featureParams” to “featureParamsOffset”
      • LookupList table: “lookups” to “lookupOffsets”
      • ConditionSet Table: “conditions” to “conditionOffsets”
      • FeatureTableSubstitutionRecord: “alternateFeatureTable” to “alternateFeatureOffset”
    • Changed LookupFlag names:
      • “rightToLeft” to “RIGHT_TO_LEFT”
      • “ignoreBaseGlyphs” to “IGNORE_BASE_GLYPHS”
      • “ignoreLigatures” to “IGNORE_LIGATURES”
      • “ignoreMarks” to “IGNORE_MARKS”
      • “useMarkFilteringSet” to “USE_MARK_FILTERING_SET”
      • “markAttachmentType” to “MARK_ATTACHMENT_TYPE_MASK”
    • Added common formats for use in the GSUB and GPOS tables, replacing formats in GSUB and GPOS chapters that were identical but with different names:
      • SequenceContextFormat1, SequenceContextFormat2, SequenceContextFormat3, and associated subtables (replacing ContextSubstFormat1/ContextPosFormat1, etc.)
      • ChainedSequenceContextFormat1, ChainedSequenceContextFormat2, ChainedSequenceContextFormat3, and associated subtables (replacing ChainContextSubstFormat1/ChainContextPosFormat1, etc.)
      • SequenceLookupRecord (replacing SubstLookupRecord/PosLookupRecord)
    • Replaced Figure 2b with a clearer illustration of language system differences.
    • Clarified optionality of features not referenced by the requiredFeatureIndex field of the LangSys table.
    • Added note regarding GSUB features being processed by applications in stages.
    • Added clarification regarding FeatureParams tables.
    • Added clarification regarding general lookup processing, and regarding filtering lookup flags in relation to the first glyph in input sequences.
    • In relation to contextual lookup types, added clarification regarding lookup flags in the main lookup table and in nested lookup tables.
    • Corrected reference to GPOS type 8 lookups (post-release erratum).
    • Corrected errors in data for Example 3.

  • charstr2.htm

    • Page removed. (The page only provided an external link, already in cff.htm.)

  • cmap.htm

    • Changed field names:
      • EncodingRecord: “offset” to “subtableOffset”
      • Format 2 subtable: “glyphIndexArray” to “glyphIdArray”
      • Format 4 subtable: “idRangeOffset” to “idRangeOffsets”
      • Format 10 subtable: “glyphs” to “glyphIdArray”
    • Added clarification regarding use of different formats.
    • Added clarification regarding subtables being used exclusively.
    • Changed guidance regarding the Macinthosh platform.
    • Added details regarding the Unicode and ISO platforms (moved from the 'name' chapter).
    • Revised description of encodings for the Windows platform.
    • Revised description of the “Custom” platform (ID 4).
    • Revised descriptions for formats 0, 2, 4, 6, 8, 10, 12, 14.
    • In description of format 4, provided details regarding purpose of searchRange, entrySelector and rangeShift fields as well as recommendations for fonts and parsing. Also corrected glyph mapping example.
    • Corrected description of the entrySelector field (post-release erratum, correction back-ported from version 1.9).

  • colr.htm

    • In BaseGlyphRecord and LayerRecord, changed field names “gID” to “glyphId”.
    • Changed general requirement regarding glyph ID 1 to a compatibility note.

  • cpal.htm

    • Changed field names:
      • “offsetFirstColorRecord” to “colorRecordsArrayOffset”
      • “offsetPaletteTypeArray” to “paletteTypesArrayOffset”
      • “offsetPaletteLabelArray” to “paletteLabelsArrayOffset”
      • “offsetPaletteEntryLabelArray” to “paletteEntryLabelsArrayOffset”
    • Clarified use of sRGB.
    • Clarified meaning of alpha values.
    • In the section on SVG and CPAL, replaced “context-fill” and “context-fill-opacity” with “currentColor”.

  • dsig.htm

    • In SignatureRecord, changed field name “offset” to “signatureBlockOffset”.
    • Corrected references for PKCS #7, PKCS #9.
    • Corrected the steps for creating a DSIG table, and clarified steps for creating a DSIG table for a TTC.
    • Removed erroneous reference to DSIG checksum field.

  • dvaraxistag_opsz.htm

    • Revised description for the Optical size axis.

  • ebdt.htm

    • Added descriptions of fields for BigGlyphMetrics, SmallGlyphMetrics.
    • Changed characterization of BitmapSize from table to record.

  • eblc.htm

    • Changed field names:
      • IndexSubtable1 and IndexSubtable3: “offsetArray” to “sbitOffsets”
      • GlyphIDOffsetPair record: “offset” to “sbitOffset”
    • Changed characterization of BitmapSize from table to record.
    • Revised description of EBLC header to incorporate BitmapSize records array.
    • Added descriptions of fields for BigGlyphMetrics, SmallGlyphMetrics.

  • ebsc.htm

    • Changed characterization of BitmapSize from table to record.

  • euro.htm

    • Removed file. (Content not part of the font format specification, available elsewhere.)

  • featurelist.htm

    • Added features 'chws', 'vchw'.

  • features_ae.htm

    • Added 'chws' feature description.
    • Modified feature descriptions: 'aalt', 'abvf', 'abvm', 'abvs', 'afrc', 'akhn', 'blwf', 'blwm', 'blws', 'calt', 'case', 'ccmp', 'cfar', 'cjct', 'clig', 'cpct', 'cpsp', 'cswh', 'curs', 'cv01' – 'cv99', 'c2pc', 'c2sc', 'dist', 'dlig', 'dnom', 'dtls', 'expt'.

  • features_fj.htm

    • Modified feature descriptions: 'falt', 'fin2', 'fin3', 'fina', 'flac', 'frac', 'fwid', 'half', 'haln', 'halt', 'hist', 'hkna', 'hlig', 'hngl', 'hoji', 'hwid', 'init', 'isol', 'ital', 'jalt', 'jp78', 'jp83', 'jp90', 'jp04'.

  • features_ko.htm

    • Deprecated 'opbd' feature.
    • Modified feature descriptions: 'kern', 'lfbd', 'liga', 'ljmo', 'lnum', 'locl', 'ltra', 'ltrm', 'mark', 'med2', 'medi', 'mgrk', 'mkmk', 'mset', 'nalt', 'nlck', 'nukt', 'numr', 'onum', 'opbd', 'ordn', 'ornm'.

  • features_pt.htm

    • Modified feature descriptions: 'palt', 'pcap', 'pkna', 'pnum', 'pref', 'pres', 'pstf', 'psts', 'pwid', 'qwid', 'rand', 'rclt', 'rkrf', 'rlig', 'rphf', 'rtbd', 'rtla', 'rtlm', 'ruby', 'rvrn', 'salt', 'sinf', 'smcp', 'smpl', 'ss01' – 'ss20', 'ssty', 'stch', 'subs', 'sups', 'swsh', 'titl', 'tjmo', 'tnam', 'tnum', 'trad', 'twid'

  • features_uz.htm

    • Added 'vchw' feature description.
    • Modified feature descriptions: 'unic', 'valt', 'vatu', 'vert', 'vhal', 'vjmo', 'vkna', 'vkrn', 'vpal', 'vrt2', 'vrtr', 'zero'.

  • fvar.htm

    • Moved recommendation regarding postScriptNameID to Recommendations.

  • gasp.htm

    • Clarified version 0 versus version 1.

  • gdef.htm

    • Changed table name: “MarkGlyphSetsTable” to “MarkGlyphSets” (table).
    • Changed field name in MarkGlyphSets table: “markGlyphSetsTableFormat” to “format”.

  • glyf.htm

    • Added clarification regarding the number of points in a simple glyph description.
    • Clarified descriptions of xMin, yMin, xMax, yMax.

  • gpos.htm

    • In BaseRecord, changed field name “baseAnchorOffset” to “baseAnchorOffsets”.
    • Removed GPOS-specific formats that were identical to formats in GSUB but with different names, replaced by common formats shared between GSUB and GPOS, described in chapter2.htm:
      • ContextPosFormat1, ContextPosFormat2, ContextPosFormat3, and associated subtables (replaced by SequenceContextFormat1, etc.)
      • ChainContextPosFormat1, ChainContextPosFormat2, ChainContextPosFormat3, and associated subtables (replaced by ChainedSequenceContextFormat1, etc.)
      • PosLookupRecord (replaced by SequenceLookupRecord)
    • In section on position lookup records, added note regarding lookup flags in a main lookup table and in nested lookup tables.

  • gsub.htm

    • Removed GSUB-specific formats that were identical to formats in GPOS but with different names, replaced by common formats shared between GSUB and GPOS, described in chapter2.htm:
      • ContextSubstFormat1, ContextSubstFormat2, ContextSubstFormat3, and associated subtables (replaced by SequenceContextFormat1, etc.)
      • ChainContextSubstFormat1, ChainContextSubstFormat2, ChainContextSubstFormat3, and associated subtables (replaced by ChainedSequenceContextFormat1, etc.)
      • SubstLookupRecord (replaced by SequenceLookupRecord)

  • hdmx.htm

    • Changed data types for numRecords, sizeDeviceRecord to unsigned types.

  • head.htm

    • Changed field name: “checkSumAdjustment” to “checksumAdjustment”.
    • Added recommendation regarding flags bit 3 in hinted fonts.
    • Clarified descriptions for xMin, yMin, xMax, yMax.

  • hhea.htm

    • Clarified descriptions for minLeftSideBearing, minRightSideBearing.
    • Revised note regarding the ascender, descender and linegap fields.

  • hmtx.htm

    • Clarified wording regarding the hMetrics and leftSideBearings arrays.
    • Clarified the left side bearing value that should be specified for empty glyphs.

  • index.htm

    • Updated version number and reference to ISO/IEC 14496-22.
    • Removed reference to the WGL4.0 character set.
    • Incorporated links to ttch01.htm, tt_instructing_glyphs.htm, tt_instructions.htm, tt_graphics_state.htm.
    • Changed links for Adobe Technical Notes #5176, #5177 to be direct, external links, not to cffspec, charstr2 pages.

  • jstf.htm

    • Changed field names in JstfPriority table:
      • “shrinkageEnableGSUB” to “gsubShrinkageEnableOffset”
      • “shrinkageDisableGSUB” to “gsubShrinkageDisableOffset”
      • “shrinkageEnableGPOS” to “gposShrinkageEnableOffset”
      • “shrinkageDisableGPOS” to “gposShrinkageDisableOffset”
      • “shrinkageJstfMax” to “shrinkageJstfMaxOffset”
      • “extensionEnableGSUB” to “gsubExtensionEnableOffset”
      • “extensionDisableGSUB” to “gsubExtensionDisableOffset”
      • “extensionEnableGPOS” to “gposExtensionEnableOffset”
      • “extensionDisableGPOS” to “gposExtensionDisableOffset”
      • “extensionJstfMax” to “extensionJstfMaxOffset”

  • kern.htm

    • In Format 2, changed field names:
      • “leftClassTable” to “leftClassOffset”
      • “rightClassTable” to “rightClassOffset”
      • “array” to “kerningArrayOffset”

  • languagetags.htm

    • Added note clarifying ISO 639 identifiers that may be listed for a given language system tag.
    • Added note about permanent reservation of 'dflt', 'DFLT'.
    • Revised details regarding ISO 639 mappings for language system tags 'AKA ', 'ATH ', 'BAD0', 'BER ', 'BML ', 'CPP ', 'FNE ', 'HAL ', 'IJO ', 'KOH ', 'KRN ', 'MYN ', 'NAH ', 'QIN ', 'SLA ', 'SRB ', 'TMH ', 'TNE ', 'TWI ', 'YCR '.
    • Corrections to show full tags 'HO ', 'WA '.
    • Revised descriptions for 'DGO ', 'DGR ', 'ZHH ', 'ZHTM'.
    • Added: 'AKB ', 'BTD ', 'BTK ', 'BTM ', 'BTX ', 'BTZ ', ZHTM.
    • Added 'DAG ' (post-release update).
    • Added 'AVN ', 'KAW ', 'LEF ', 'WCI ' (post-release update).
    • Added 'CTT ', 'HAI0', 'HEI ', 'HMD ', 'HMZ ', 'IRU ', 'KWK ', 'LPO ', 'RHG ', 'SFM ', 'TLI ', 'XUB ', 'XUJ ', 'YGP ', 'YNA ', 'YWQ ' (post-release update).
    • Revised ISO 639 mapping details for 'SXT ' (post-release update.)

  • loca.htm

    • Revised recommended for local offsets to be word aligned.

  • math.htm

    • Changed field name in MathValueRecord: “deviceTableOffset” to “deviceOffset”.
    • Changed flag name “fExtender” to “EXTENDER_FLAG”.
    • For fields that are values in design grid units, changed data types from int16 to FWORD, and from uint16 to UFWORD.
    • Clarified meaning of “shift” in MathConstants fields.
    • Clarified default rule thickness.
    • Added clarification of suggested value for spaceAfterScript.
    • Added suggested value for radicalKernAfterDegree.

  • maxp.htm

    • Changed type for the version field from Fixed to Version16Dot16.

  • meta.htm

    • Corrected description of example Hant-HK.

  • name.htm

    • Changed field names:
      • Header: “format” to “version”
      • Version 0 and version 1 headers: “stringOffset” to “storageOffset”
      • LangTagRecord: “offset” to “langTagOffset”
      • NameRecord: “offset” to “stringOffset”
    • Re-organized content to move tables of platform, encoding and language IDs to the end of the chapter. Also removed details relevant only to the 'cmap' table.
    • Updated language and region strings for Windows language ID 042F.
    • Changed the language name for Windows language ID 081D to “Swedish”.

  • os2.htm

    • Corrected details for Unicode range fields regarding bit 92 and versions 3, 4.

  • otff.htm

    • Changed field names:
      • In TableRecord: “checkSum” to “checksum”.
      • In TTC Header version 1.0 and version 2.0: “offsetTable” to “tableDirectoryOffsets”.
    • Clarified that LONGDATETIME values are in UTC time.
    • Defined a Version16Dot16 type (replacing Fixed used for table version).
    • Clarified use of “record” and “table” in describing defined structures.
    • Clarifed statement regarding file extensions.
    • Removed historic reference to Multiple Master support being discontinued. (Details are retained in the change log.)
    • Revised terminology, removing use of “offset table” and making consistent use of “table directory”.
    • Re-organized description of TableDirectory and TableRecord array, adding tableRecords[] as a member in TableDirectory.
    • Provided details regarding purpose of searchRange, entrySelector and rangeShift fields as well as recommendations for fonts and parsing.
    • Moved statement of the requirement for four-byte table offsets to follow description of table records.
    • Clarified checksum calculation for tables with length not a multiple of four.
    • Clarified calculation of the 'head' table checksum and checksumAdjustment, and checksums in collection files.
    • Clarified location of DSIG table within a TTC file.
    • Added clarifications regarding custom, vendor-defined tags.

  • otvarcommonformats.htm

    • Changed field name in DeltaSet record: “DeltaData” to “deltaData”.
    • Added text defining special meaning of delta-set outer- and inner-level indices 0xFFFF/0xFFFF as an indication of no variation data.
    • Added constraint on VariationRegionList.regionCount to be less than 32,768 (high bit reserved).
    • Added note regarding NULL offsets in the itemVariationDataOffsets array.
    • In DeltaSet record, revised description of deltaSet array to indicate number of elements in array, not byte length.

  • otvaroverview.htm

    • Moved description of normalization process and example from avar.htm into this chapter.

  • overview.htm

    • Complete re-write of the overview content.

  • pclt.htm

    • Revised member names to use camel case.
    • Clarified note on discouraged usage.

  • post.htm

    • Changed type for the version field from Fixed to Version16Dot16.
    • Clarified the description of version 2.0; this includes changing the type and field name for the string data.
    • Clarified encoding of name strings and moved requirements from Recommendations to here.

  • recom.htm

    • Removed byte ordering and 'OS/2' sections.
    • Revised the table alignment section.
    • Revised the 'cmap' recommendations.
    • Added 'fvar' section with recommendation regarding postScriptNameID.
    • 'name' section: Revised guidance regarding names for the Macintosh platform.
    • 'post' section: Moved name string requirements to 'post' table chapter. Removed redundant and obsolete recommendations.

  • sbix.htm

    • Revised descriptions of originOffsetX, originOffsetY, and provided clarification regarding positioning of the bitmap graphic.

  • scripttags.htm

    • Added script tags for new scripts in Unicode 12 and Unicode 13.
    • Corrected script tag for Yi. (Post-release erratum.)

  • stat.htm

    • Relaxed constraint on name IDs used for AxisRecord.axisNameID.
    • Revised constraints and recommendations regarding separate axis value tables having the same information.
    • For AxisValueFormat2, clarified details regarding touching and overlapping ranges.
    • For AxisValueFormat4, clarified precedence when two tables are partial matches, and clarified the axis ordering to be assumed .
    • Adopted consistent spelling for flag names: OLDER_SIBLING_FONT_ATTRIBUTE and ELIDABLE_AXIS_VALUE_NAME.
    • Revised chapter for greater clarity.

  • svg.htm

    • Changed field name “offsetToSVGDocumentList” to “svgDocumentListOffset”.
    • Clarified note regarding glyph advances not changing due to animations.

  • tt_graphics_state.htm

    • Corrected the list of instructions affected by single_width_cut_in and single_width_value, and clarified the units for single_width_value.

  • tt_instructing_glyphs.htm

    • Removed incorrect statement regarding single_width_cut_in applying to indirect instructions.

  • tt_instructions.htm

    • Corrected figures illustrating stack operations for JROF.
    • Correction in details for SDPVTL.
    • Corrected figures for SFVFS, SZP1, SMD, ALIGNRP, GC.
    • Clarified ISECT and corrected figure.
    • Clarified units for SSW.

  • ttinst.htm

    • Removed file: links to child pages incorporated into index.htm; introductory paragraph incorporated into ttch01.htm.

  • ttochap1.htm

    • Replaced Figure 1h with a clearer illustration of language system differences.
    • Consolidated “TrueType versus OpenType Layout” section into the “OpenType Layout at a glance” section.

  • vdmx.htm

    • In VDMX header, changed field name “offset” to “vdmxGroupOffsets”.

  • vhea.htm

    • Clarified scope of usage for the table.
    • Changed type for the version field from Fixed to Version16Dot16.
    • Revised descriptions of vertTypoAscender, vertTypoDescender.

  • wgl4.htm, wgl4b.htm, wgl4c.htm, wgl4d.htm, wgl4e.htm

    • Removed files. (Content was not part of the font format specification; it remains available elsewhere.)

Version 1.8.3

Released August 2018

Minor editorial changes were made in the following chapters: base.htm, baselinetags.htm, cbdt.htm, cblc.htm, cff.htm, cff2.htm, cff2charstr.htm, changes.htm, chapter2.htm, cmap.htm, colr.htm, cpal.htm, cvar.htm, dsig.htm, dvaraxisreg.htm, dvaraxistag_ital.htm, dvaraxistag_opsz.htm, dvaraxistag_slnt.htm, dvaraxistag_wdth.htm, dvaraxistag_wght.htm, ebdt.htm, eblc.htm, ebsc.htm, featurelist.htm, features_ae.htm, features_fj.htm, features_ko.htm, features_pt.htm, features_uz.htm, featuretags.htm, fvar.htm, gasp.htm, gdef.htm, glyf.htm, gpos.htm, gsub.htm, gvar.htm, hdmx.htm, head.htm, hhea.htm, hmtx.htm, hvar.htm, index.htm, jstf.htm, kern.htm, languagetags.htm, ltsh.htm, math.htm, merg.htm, meta.htm, mvar.htm, name.htm, namesmp.htm, os2.htm, otff.htm, otvarcommonformats.htm, otvaroverview.htm, pclt.htm, post.htm, recom.htm, sbix.htm, scripttags.htm, stat.htm, svg.htm, ttch01.htm, ttochap1.htm, ttoreg.htm, vdmx.htm, vhea.htm, vmtx.htm, vorg.htm, vvar.htm.

The editorial changes include applying a convention for tag values: single, straight quotation marks are used for lowercase tags; they are not used for uppercase tags except when extra clarification is required, such as when a tag has trailing spaces; and marks are not when a tag is used like an object name, as in “head.macStyle”, or when used like a function name, as in “cmap(j)”.

In the summary of changes below, details given above are not repeated.

Summary of Changes:

  • base.htm
    • Corrected figure 5c.
  • cmap.htm
    • Corrected field names for format 4.
    • Eliminated outdated references to “UCS-2” and “UCS-4”.
    • Added comments regarding use of formats 8, 10.
    • Corrected typo in glyphId index value equation from “startCount” to “startCode”.
  • cff2.htm
    • Revised name of operand for blend operator.
    • Corrected max number of glyphs supported by FDSelect Format 3 from 65536 to 65536. (Post-release erratum.)
  • changes.htm
    • Re-organized how systemic and minor editorial changes are recorded for Version 1.8.1.
    • Removed reference to proposals.htm (this legacy page was a companion to this specification but not part of it).
    • Replaced references to default.htm (no longer used) with index.htm.
    • Added missing change to ttinst1.doc in OpenType 1.5. (Post-release erratum.)
  • chapter2.htm
    • Corrected the number of GSUB lookup types (eight).
    • Clarifed description of Coverage Indexes for Coverage Format 2.
  • dsig.htm
    • Revised statments regarding anticipated use of signatures.
  • ebdt.htm
    • Corrected text typo from “EDBT” to “EBDT” in the Header.
  • eblc.htm
    • Corrected text typo from “EDBT” to “EBDT” in the first paragraph.
    • Corrected text from “16-bit alignment” to “32-bit alignment”.
  • ebsc.htm
    • Corrected text typo from “EBLC” to “EBSC” in “EBSC Header”.
  • features_ko.htm
    • Corrected description for 'med2'.
  • features_pt.htm
    • Corrected example for 'ssty'. (Post-release erratum.)
    • Corrected Tag: 'ssty'. (Post-release erratum.)
  • featuretags.htm
    • Revised comments on implementation of 'init' feature for Arabic text for consistency with description of the 'init' feature.
  • gdef.htm
    • Revised field names in MarkGlyphSetsTable format to conform to conventions.
  • glyf.htm
    • Clarified the description of simple glyph flags.
    • Added the OVERLAP_SIMPLE flag.
    • Corrected statement regarding numberOfContours for simple glyph descriptions. (Post-release erratum.)
  • gpos.htm
    • Corrected description of the offset to Device / VariationIndex tables within ValueRecord.
    • Clarified placement and advance effects of lookup types 1 – 6.
  • grstate.doc
  • gsub.htm
    • For Single Substitition Format 1, indicated that addition is modulo 65536.
    • Corrected error in example 7: DashAndSpaceSubRuleSet is at offset SubRuleSet[1].
  • hhea.htm
    • Removed references to historic platforms.
  • index.htm
    • Updated version number and reference to ISO/IEC 14496-22.
    • Removed mention of Microsoft Word documents.
  • instgly.doc
  • jstf.htm
    • Revised field name, jsftLangSysOffset, to follow conventions.
  • kern.htm
    • Removed references to historic platforms.
  • languagetags.htm
    • Added 'KJZ ', 'MFA ', 'TSJ ', 'XKF '.
    • Added additional ISO 639 mappings.
  • math.htm
    • Revised descriptions for better clarity.
    • Re-ordered content in section on MathKernInfo table for better clarity.
    • In description of formats for MathItalicsCorrectionInfo, MathTopAccentAttachment, MathKernInfo and MathVariants, clarified that the count fields must be the same as the number of glyph IDs referenced in the Coverage tables.
    • Revised structure and field names to follow conventions.
  • maxp.htm
    • Clarified maxStackElements.
  • name.htm
    • Replaced obsolete recommendation to have Macintosh strings for legacy version-control implementations with advisory that apps might display incorrect strings.
    • Added link to BCP 47.
    • Eliminated outdated references to “UCS-2” and “UCS-4”.
    • Corrected Macintosh platform language ID for Inuktitut; corrected typos (Quechua, Tagalog).
    • In the table for the Platform ID enumeration, corrected the description for language IDs for Platform ID 0 (error introduced in version 1.5).
    • Revised descriptions for name IDs 1 and 2.
  • os2.htm
    • Incorporated relevant information regarding OS/2 versions 0 to 4. (Separate pages removed.)
    • Added note regarding truncated version 0 definition in Apple’s TrueType Reference Manual.
    • Corrected units for xAvgCharWidth.
    • fsType: Clarified “embedding”; revised presentation of flags; noted that bit 0 is permanently reserved.
    • yStrikeoutSize, yStrikeoutPosition: Removed legacy statements intended for bitmap fonts; added reference to post.underlineThickness.
    • panose: Clarified the contingent meaning of bytes other than the first byte.
    • ulUnicodeRange: Eliminated outdated references to “UCS-2” and “UCS-4”; added note that available bits are exhausted, and reference to 'dlng' and 'slng' tags in the 'meta' table; clarified some issues for early OS/2 versions.
    • achVendID: Revised description.
    • sTypoAscender, sTypoDescender, sTypoLineGap: Revised descriptions; clarified the non-requirement that sTypoAscender - sTypoDescender equal unitsPerEm.
    • usWinAscent, usWinDescent: Revised description; clarified clipping behavior in Windows GDI, and added note regarding interaction with VDMX.
    • Added more information about setting default line metric values in variable fonts, and varying line metric values in variable fonts.
    • Added more information about setting usLowerOpticalPointSize and usUpperOpticalPointSize values in variable fonts.
  • os2ver0.htm, os2ver1.htm, os2ver2.htm, os2ver3.htm, os2ver4.htm
    • Pages removed; relevant content integrated into os2.htm.
  • otff.htm
    • Added .TTC and .OTC to cited filename extensions, and removed recommendation details, which are already provided in the Recommendations chapter.
    • Added table and design-variation axis to items identified using Tag.
    • Moved the specification for valid Tag values from the Table Record description into the data types section.
    • Made clarifications regarding representations of version numbers
    • Changed the data type for the first member of the Table Record to Tag, and changed the member name and description.
    • For underlineThickness, added reference to OS/2.strikeoutSize.
  • otvaroverview.htm
    • Corrected the arithmetic details in the last part of the example in the Interpolation Example section.
    • Corrected typo “wiht” to “with” in “Coordinate Scales and Normalization”.
  • recom.htm
    • Added filename recommendation related to CFF and revised wording related to font collections.
    • Eliminated outdated references to “UCS-2”, “UCS-4” and legacy products in 'cmap' section.
    • Removed obsolete guidance for use of 'vrt2' feature in CJK fonts.
  • stat.htm
    • Revised the introduction to Axis Value Tables for better clarity.
    • Corrected typo changing “appliations” to “applications”.
  • svg.htm
    • Revised organization and descriptive text for better clarity.
    • Revised structure names to follow conventions.
    • Prohibited use of “HTML dialect” SVG documents.
    • Restricted usage of XML namespace declarations.
    • Limited capabilities to SVG 1.1. Deprecated use of context-* properties from SVG2 (support was required in earlier versions).
    • Added section detailing SVG 1.1 capability requirements and restrictions. (Several capabilities not clearly discussed in earlier versions are now discouraged or not supported.)
    • Clarified use of CSS custom properties and integration of CPAL, including interpretation of CPAL alpha values.
    • Added use of currentColor (supersedes use of context-fill, context-stroke).
    • Clarified relationship of coordinate system and viewport to glyph design grid, and also viewport clip behavior.
    • Removed references to “user agent style sheets”.
    • Removed section on security considerations and glyph rendering restrictions (superseded by the added section on SVG 1.1 capability requirements and restrictions).
    • Added Example 1.
    • Revised Example 5, replacing context-fill with currentColor.
  • ttinst.htm
    • Revised links to refer to content ported from Microsoft Word files to Web pages. (Post-release update, August 2018.)
  • ttinst1.doc
  • ttinst2.doc
  • tt_instructions.htm
    • Corrected MIRP Code range to 0xE0 - 0xFF.
    • Corrected errors introducted when porting from Word documents (some changes from earlier versions were not retained). (Post-release erratum.)
    • Changed “NPUSHB” to “NPUSHW” in GETVARIATION. (Post-release erratum.)
    • Corrected error in “FLIPRGOFF” regarding on-curve versus off-curve points. (Post-release erratum.)
    • Removed extra, incorrect uses from “IUP”. (Post-release erratum.)
    • Corrected text in GETVARIATION[] normalized coordinates. (Post-release erratum.)
    • Corrected error in code range of MIRP inadvertently introduced when porting from Word documents. (Post-release erratum.)
    • Corrected error in description of “logical OR” inadvertently added when porting from Word documents. (Post-release erratum.)
    • Removed incorrect text inadvertently added to description of Round to Half Grid (RTHG) when porting from Word documents. (Post-release erratum.)
  • ttochap1.htm
    • Fixed typo in image (fig1i.gif).
  • vhea.htm
    • Made corrections to the description for vertTypoDescender.

Version 1.8.2

Released July 2017.

Many editorial changes have been made, including revision of structure and field names in several chapters to conform to conventions used across this specification. Such changes were made in the following chapters:

A significant editorial change pertains to documentation of design-variation axes and axis tags: previously, these were documented within the 'fvar' table chapter. The axis tags are also used in other tables, however, and may be relevant for non-variable fonts. Also, the set of registered axes may grow over time. Hence, documentation of axes and axis tags has been moved to a separate section, OpenType Design-Variation Axis Tag Registry.

Minor editorial changes were made in the following chapters: avar.htm, base.htm, cbdt.htm, cblc.htm, cff.htm, cff2.htm, cff2charstr.htm, chapter2.htm, cmap.htm, colr.htm, cpal.htm, cvar.htm, dsig.htm, ebdt.htm, eblc.htm, ebsc.htm, features_fj.htm, fvar.htm, gasp.htm, gdef.htm, glyf.htm, gpos.htm, gsub.htm, gvar.htm, hdmx.htm, head.htm, hhea.htm, hmtx.htm, hvar.htm, jstf.htm, math.htm, maxp.htm, merg.htm, mvar.htm, os2.htm, otff.htm, otvarcommonformats.htm, otvaroverview.htm, post.htm, sbix.htm, scripttags.htm, stat.htm, vvar.htm, wgl4b.htm.

In the summary of changes below, details given above are not repeated.

Summary of Changes:

  • avar.htm
    • Clarified requirements on AxisValueMap records within a SegmentMap.
  • cff.htm
    • Added note about Name INDEX entry, name ID 6 and collections.
  • cff2.htm
    • In Top DICT (section 7), indicated that FontMatrix operator is required only if head.unitsPerEm does not equal 1000, and limited the FontMatrix operand array values. Also deprecated use of FontMatrix operator in Font DICTs (section 10 and Appendix C).
    • Corrected description of blend and vsindex operators (section 8).
    • Corrected description of operands for the Private operator (section 10).
    • Corrected error in numeric range of reserved two-byte DICT operators (Appendix C).
    • Removed the maxstack operator.
  • cff2charstr.htm
    • In 3.2, CharString Number Encoding, corrected the described range of values represented for byte values 251 to 254.
    • Revised argument stack limit in Appendix B to 513, and removed reference to maxstack operator.
  • chapter2.htm
    • Relaxed constraint on DFLT script table and LangSysCount.
  • cmap.htm
    • Clarified description for defaultUVSOffset and nonDefaultUVSOffset.
    • Re-organized introductory paragraphs and details on platform/encoding IDs.
  • dvaraxisreg.htm
    • Created new page.
  • dvaraxistag_ital.htm
    • Created new page.
  • dvaraxistag_opsz.htm
    • Created new page.
  • dvaraxistag_slnt.htm
    • Created new page.
  • dvaraxistag_wdth.htm
    • Created new page.
  • dvaraxistag_wght.htm
    • Created new page.
  • features_ae.htm
    • Revised 'ccmp' feature description.
  • features_ko.htm
    • Corrected the friendly name for the 'med2' feature.
  • fvar.htm
    • Added a new flag definition for VariationAxisRecord.
    • Removed Variation Axis Tags section and made reference instead to OpenType Design-Variation Axis Tag Registry page.
  • gasp.htm
    • Revised documentation of behavior flags, and indicated that reserved bits must be set to zero.
  • glyf.htm
    • Added clarifying information about table organization, side bearings, point numbers, scale for coordinate values, packed representation of flags and coordinates in simple glyph descriptions, and the SCALED_COMPONENT_OFFSET and UNSCALED_COMPONENT_OFFSET composite glyph flags.
    • Clarified use of negative numberOfContours values to indicate composite glyphs, and the recommendation that -1 be used.
    • Revised documentation of flags, and indicated that reserved bits must be set to zero.
  • grstate.doc
  • gvar.htm
    • Amend the algorithm for inferring deltas of un-referenced points to avoid division by zero and to completely cover possible cases.
  • hmtx.htm
    • Revise errors in the informative description.
  • index.htm
    • Version update.
    • Added link to OpenType Design-Variation Axis Tag Registry page.
    • Removed mention of Microsoft Word documents. (Post-release update, August 2018.)
  • instgly.doc
  • languagetags.htm
    • Added CCHN.
  • meta.htm
    • Corrected the format of the table version (post-release erratum).
  • mvar.htm
    • Changed reference for variation axis tags from 'fvar' chapter to OpenType Design-Variation Axis Tag Registry page.
  • name.htm
    • Clarified that the string data referenced by 3/1 or 3/0 name records must be encoded in UTF-16BE.
    • Revised descriptions for name IDs 1, 2 and 4, and also the paragraph describing key names for Microsoft platforms.
  • os2.htm
    • Changed reference for variation axis tags from 'fvar' chapter to OpenType Design-Variation Axis Tag Registry page.
    • Corrected link to PANOSE specification (post-release erratum).
  • os2ver0.htm
    • Corrected link to PANOSE specification (post-release erratum).
  • os2ver1.htm
    • Corrected link to PANOSE specification (post-release erratum).
  • os2ver2.htm
    • Corrected link to PANOSE specification (post-release erratum).
  • os2ver3.htm
    • Corrected link to PANOSE specification (post-release erratum).
  • os2ver4.htm
    • Corrected link to PANOSE specification (post-release erratum).
  • otff.htm
    • Clarify that table lengths measure a contiguous byte range encompassing the data for the table.
  • pclt.htm
    • Corrected the data type of the MajorVersion field (post-release erratum).
    • Corrected the description for SerifStyle (post-release erratum).
  • post.htm
    • Changed reference for variation axis tags from 'fvar' chapter to OpenType Design-Variation Axis Tag Registry page.
    • Corrected link to Adobe glyph naming guide (post-release erratum).
  • recom.htm
    • Clarified that the string data referenced by 3/0 name records must be encoded in UTF-16BE.
    • For optical size variants, clarified representation within a STAT axis value table for an upper text size of effective infinity.
    • Corrected link to Adobe glyph naming guide (post-release erratum).
    • Corrected link to PANOSE specification (post-release erratum).
  • scripttags.htm
    • Removed details on processing of script tags, and replaced with link to details in the OpenType Layout Common Table Formats (post-release erratum).
    • Added tags for additional scripts in Unicode 10, Unicode 11 (post-release update).
  • stat.htm
    • Added axis value table format 4.
    • Revised Introduction to clarify purpose and use of the table as a whole; and revised introduction in the Axis Value Tables section to clarify purpose and use of axis value tables.
    • Added clarifications regarding axes, mapping to legacy font-family models, and serialized representation of document text-formatting properties.
    • Clarified representation of effective infinity and negative infinity in range min/max fields of format 2 axis value tables.
    • Added note regarding use of OlderSiblingFontAttribute.
    • Changed reference for tag requirements from 'fvar' table to the Opentype Design Variation Tag Registry.
    • Revised the axis ordering in example 3 to reflect recommendation given in Axis Value Tables section.
  • ttinst.htm
    • Revised links to refer to content ported from Microsoft Word files to Web pages. (Post-release update, August 2018.)
  • ttinst1.doc
  • ttinst2.doc
  • ttochap1.htm
    • Added hyperlink to OpenType Mirroring Pairs List file (ompl.txt).
  • tt_instructions.htm
    • Corrected errors introduced when porting from Word documents (some changes from earlier versions were not retained). (Post-release erratum.)
    • Corrected error in description of “logical OR” inadvertently added when porting from Word documents. (Post-release erratum.)
    • Removed incorrect text inadvertently added to description of Round to Half Grid (RTHG) when porting from Word documents. (Post-release erratum.)
    • Corrected error in code range of MIRP inadvertently introduced when porting from Word documents. (Post-release erratum.)
  • vhea.htm
    • Corrected the calculation given in the description of yMaxExtent (post-release erratum).
  • wgl4.htm
    • Corrected link to Adobe glyph naming guide (post-release erratum).
  • wgl4b.htm
    • Corrected link to Adobe glyph naming guide (post-release erratum).
  • wgl4c.htm
    • Corrected link to Adobe glyph naming guide (post-release erratum).
  • wgl4d.htm
    • Corrected link to Adobe glyph naming guide (post-release erratum).
  • wgl4e.htm
    • Corrected link to Adobe glyph naming guide (post-release erratum).

Version 1.8.1

Released January 2017.

Many editorial changes have been made, including global changes to the names of data types used. Some technical corrections were made that do not affect structure definitions. One structure change was introduced: a field was added in the STAT table.

Changes to names of data types were made in various chapters, as follows:

Minor editorial changes were made in the following chapters: base.htm, cbdt.htm, cblc.htm, cff2.htm, cff2charstr.htm, chapter2.htm, colr.htm, cvar.htm, ebdt.htm, eblc.htm, ebsc.htm, fvar.htm, gpos.htm, gsub.htm, gvar.htm, hdmx.htm, hmtx.htm, hvar.htm, index.htm, jstf.htm, languagetags.htm, loca.htm, math.htm, otff.htm, otvarcommonformats.htm, otvaroverview.htm, post.htm, stat.htm, vdmx.htm.

In the summary of changes below, details given above are not repeated.

Summary of Changes:

  • avar.htm
    • Corrected header definition, adding missing reserved field (post-release erratum).
    • Corrected SegmentMaps record definition, showing axisValueMaps as an array (post-release erratum).
  • cff2.htm
    • Revised Table 1, CFF Data Layout.
    • Revised description of operands in section 4, DICT Data, including removal of the boolean operand type from Table 6.
    • Revised description of Top DICT data (section 7).
    • Deleted section 8, Glyph Organization
    • Revised description of CharString INDEX (now section 8).
    • Revised description of local and global subr indices (now section 9).
    • Revised description of Font DICT INDEX, Font DICTs and FDSelect (now section 10).
    • Revised description of Private DICT Data (now section 11).
    • Revised description of extensions for Font Variations (now section 12).
    • Added example CFF2 table in Appendix A.
    • Revised description of differences from CFF 1 (sections D1 to D4 of Appendix D).
    • Deleted sections D5 and D6 from Appendix D.
  • cff2charstr.htm
    • Revised description of subroutines (section 2.3).
    • Revised description of CFF2 CharString organization (section 3.1), and CharString number encoding (section 3.2).
    • Correction in Table 1, “CFF2 CharString Encoding Values” for byte values 251 – 254.
    • Revised description of CharString operators (section 4).
    • Revised description of path construction operators (section 4.1). Note that changes to the individual operator descriptions are editorial only.
    • Revised description of finishing a CharString outline definition (section 4.2).
    • Revised description of subroutine operators (section 4.4).
    • Revised description of variation data operators (section 4.5).
    • Revised summaries of one- and two-byte operators in Appendix A.
    • In Appendix B, revised description of argument stack limits, and removed TransientArray elements from the list of limits.
    • Deleted Appendix C, “Compatibility and Deprecated Operators”.
  • chapter2.htm
    • Correction of type of MarkFilteringSet index in Lookup table from “unit16” (sic) to uint16.
    • Removed erroneous reference to ConditionSet version.
    • Renamed FeatureVariationRecordsCount in FeatureVariations table to FeatureVariationRecordCount
    • Renamed AlternateFeatureTableOffset field in FeatureTableSubstitutionRecord to AlternateFeatureTable.
  • cmap.htm
    • Revised presentation of formats to give names to records and to integrate record arrays into the presentation of the format for the parent structure containing the array.
  • dsig.htm
    • Changed field names away from Hungarian notation (“ulVersion” to “version”, etc.).
  • features_pt.htm
    • Added note for the 'size' feature regarding the STAT table.
  • fvar.htm
    • Changed the countSizePairs field to permanently reserved, and removed note about this field.
    • Clarified usage of the axisSize and instanceSize fields.
    • Clarified expected behavior if axisCount is zero or if instanceCount is zero.