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head table ​

Contains global font metadata — units per em, bounding box, creation dates, and format flags.

Scope ​

  • Format family: Shared SFNT
  • Table tag in JSON: head

Specs ​

JSON Skeleton ​

This skeleton reflects fields currently parsed/written by Font Flux JS for this table.

json
{
  "tables": {
    "head": {
      "majorVersion": 0,
      "minorVersion": 0,
      "fontRevision": 0,
      "checksumAdjustment": 0,
      "magicNumber": 0,
      "flags": 0,
      "unitsPerEm": 0,
      "created": 0,
      "modified": 0,
      "xMin": 0,
      "yMin": 0,
      "xMax": 0,
      "yMax": 0,
      "macStyle": 0,
      "lowestRecPPEM": 0,
      "fontDirectionHint": 0,
      "indexToLocFormat": 0,
      "glyphDataFormat": 0,
      "_checksum": 0
    }
  }
}

Top-level Fields ​

  • majorVersion - number (0..65535) [spec type: uint16] (must be 1)
  • minorVersion - number (0..65535) [spec type: uint16] (must be 0)
  • fontRevision - number (16.16 fixed) [spec type: Fixed] (16.16 fixed-point)
  • checksumAdjustment - number [spec type: uint32] (global font checksum adjustment)
  • magicNumber - number [spec type: uint32] (must be 0x5F0F3CF5)
  • flags - number (0..65535) [spec type: uint16]
  • unitsPerEm - number (0..65535) [spec type: uint16] (16–16384)
  • created - number (seconds since 1904-01-01 UTC) [spec type: LONGDATETIME] (seconds since 1904-01-01 00:00 UTC)
  • modified - number (seconds since 1904-01-01 UTC) [spec type: LONGDATETIME] (seconds since 1904-01-01 00:00 UTC)
  • xMin - number (-32768..32767) [spec type: int16]
  • yMin - number (-32768..32767) [spec type: int16]
  • xMax - number (-32768..32767) [spec type: int16]
  • yMax - number (-32768..32767) [spec type: int16]
  • macStyle - number (0..65535) [spec type: uint16]
  • lowestRecPPEM - number (0..65535) [spec type: uint16]
  • fontDirectionHint - number (-32768..32767) [spec type: int16] (deprecated, set to 2)
  • indexToLocFormat - number (-32768..32767) [spec type: int16] (0 = short offsets, 1 = long)
  • glyphDataFormat - number (-32768..32767) [spec type: int16] (0 for current format)

Additional Nested Keys Seen In Implementation ​

  • majorVersion
  • minorVersion
  • fontRevision
  • checksumAdjustment
  • magicNumber
  • flags
  • unitsPerEm
  • created
  • modified
  • xMin
  • yMin
  • xMax
  • yMax
  • macStyle
  • lowestRecPPEM
  • fontDirectionHint
  • indexToLocFormat
  • glyphDataFormat

Notes ​

  • Preserve _checksum for stable round-tripping.
  • If a table is only partially understood, prefer keeping unknown bytes in _raw instead of dropping data.
  • Validate with .validate() after edits.