'head' - Font Header

This table gives global information about the font. The bounding box values should be computed using only glyphs that have contours. Glyphs with no contours should be ignored for the purposes of these calculations.

Type

Name

Description

Fixed

Table version number

0x00010000 for version 1.0.

Fixed

fontRevision

Set by font manufacturer.

ULONG

checkSumAdjustment

To compute: set it to 0, sum the entire font as ULONG, then store 0xB1B0AFBA - sum.

ULONG

magicNumber

Set to 0x5F0F3CF5.

USHORT

flags

Bit 0 - baseline for font at y=0;

Bit 1 - left sidebearing at x=0;

Bit 2 - instructions may depend on point size;

Bit 3 - force ppem to integer values for all internal scaler math; may use fractional ppem sizes if this bit is clear;

Bit 4 - instructions may alter advance width (the advance widths might not scale linearly);

Note: All other bits must be zero.

USHORT

unitsPerEm

Valid range is from 16 to 16384

longDateTime

created

International date (8-byte field).

longDateTime

modified

International date (8-byte field).

FWord

xMin

For all glyph bounding boxes.

FWord

yMin

For all glyph bounding boxes.

FWord

xMax

For all glyph bounding boxes.

FWord

yMax

For all glyph bounding boxes.

USHORT

macStyle

Bit 0 bold (if set to 1); Bit 1 italic (if set to 1)

Bits 2-15 reserved (set to 0).

USHORT

lowestRecPPEM

Smallest readable size in pixels.

SHORT

fontDirectionHint

0 Fully mixed directional glyphs;

1 Only strongly left to right;

2 Like 1 but also contains neutrals;

-1 Only strongly right to left;

-2 Like -1 but also contains neutrals.

SHORT

indexToLocFormat

0 for short offsets, 1 for long.

SHORT

glyphDataFormat

0 for current format.


Note that macStyle bits must agree with the 'OS/2' table fsSelection bits. The fsSelection bits are used over the macStyle bits in Microsoft Windows. The PANOSE values and 'post' table values are ignored for determining bold or italic fonts.

The Date format used in this table follows the Macintosh convention of the number of seconds since 1904 (see Apple's Inside Macintosh series).