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# Font Info – Masters Custom Parameters

Use entries in the Custom Parameter field to specify more settings.

Values are interpolated if defined in all masters. Master parameters override all font-wide settings and parameters, but are overridden by instance-level settings and parameters.

## Add a Parameter

To add a parameter, click on the green plus symbol , select or type a property, and enter a value.
You can also copy and paste parameters.

Glyphs accepts these master-level parameters:

Custom Parameter

Description

typoAscenderinteger

Ascender value. Corresponds to the OpenType OS/2 table sTypoAscender field. ‘The typographic ascender for this font. Remember that this is not the same as the Ascender value in the hhea table, which Apple defines in a far different manner. One good source for sTypoAscender in Latin based fonts is the Ascender value from an AFM file. For CJK fonts see below.

The suggested usage for sTypoAscender is that it be used in conjunction with unitsPerEm to compute a typographically correct default line spacing. The goal is to free applications from Macintosh or Windows-specific metrics which are constrained by backward compatibility requirements. These new metrics, when combined with the character design widths, will allow applications to lay out documents in a typographically correct and portable fashion. These metrics will be exposed through Windows APIs. Macintosh applications will need to access the sfnt resource and parse it to extract this data from the “OS/2” table.

For CJK (Chinese, Japanese, and Korean) fonts that are intended to be used for vertical writing (in addition to horizontal writing), the required value for sTypoAscender is that which describes the top of the of the ideographic em-box. For example, if the ideographic em-box of the font extends from coordinates 0,-120 to 1000,880 (that is, a 1000 × 1000 box set 120 design units below the Latin baseline), then the value of sTypoAscender must be set to 880. Failing to adhere to these requirements will result in incorrect vertical layout.’

typoDescenderinteger

Descender value. Corresponds to the OpenType OS/2 table sTypoDescender field. ‘The typographic descender for this font. Remember that this is not the same as the Descender value in the hhea table, which Apple defines in a far different manner. One good source for sTypoDescender in Latin based fonts is the Descender value from an AFM file. For CJK fonts see below.

The suggested usage for sTypoDescender is that it be used in conjunction with unitsPerEm to compute a typographically correct default line spacing. The goal is to free applications from Macintosh or Windows-specific metrics which are constrained by backward compatability requirements. These new metrics, when combined with the character design widths, will allow applications to lay out documents in a typographically correct and portable fashion. These metrics will be exposed through Windows APIs. Macintosh applications will need to access the sfnt resource and parse it to extract this data from the “OS/2” table (unless Apple exposes the “OS/2” table through a new API).

For CJK (Chinese, Japanese, and Korean) fonts that are intended to be used for vertical writing (in addition to horizontal writing), the required value for sTypoDescender is that which describes the bottom of the of the ideographic em-box. For example, if the ideographic em-box of the font extends from coordinates 0,-120 to 1000,880 (that is, a 1000 × 1000 box set 120 design units below the Latin baseline), then the value of sTypoDescender must be set to -120. Failing to adhere to these requirements will result in incorrect vertical layout.’

typoLineGapinteger

Line gap value. Corresponds to the OpenType OS/2 table sTypoLineGap field. ‘The typographic line gap for this font. Remember that this is not the same as the LineGap value in the hhea table, which Apple defines in a far different manner.

The suggested usage for usTypoLineGap is that it be used in conjunction with unitsPerEm to compute a typographically correct default line spacing. Typical values average 7–10% of units per em. The goal is to free applications from Macintosh or Windows-specific metrics which are constrained by backward compatability requirements. These new metrics, when combined with the character design widths, will allow applications to lay out documents in a typographically correct and portable fashion.’

smallCapHeightinteger

A vertical metric for smallcaps. The algorithm for automatic creation of alignment zones respects this value.

winAscentnon-negative integer

Ascender value. Corresponds to the OpenType OS/2 table usWinAscent field.

winDescentnon-negative integer

Descender value. Corresponds to the OpenType OS/2 table usWinDescent field.

vheaVertAscenderinteger

Ascender value. Corresponds to the OpenType vhea table vertTypoAscender field.

vheaVertDescenderinteger

Descender value. Corresponds to the OpenType vhea table vertTypoDescender field.

vheaVertLineGapinteger

Line gap value. Corresponds to the OpenType vhea table vertTypoLineGap field.

hheaAscenderinteger

Ascender value. Corresponds to the OpenType hhea table Ascender field. ‘Typographic ascent (distance from baseline of highest ascender).’

hheaDescenderinteger

Descender value. Corresponds to the OpenType hhea table Descender field. ‘Typographic descent (distance from baseline of lowest descender).’

hheaLineGapinteger

Line gap value. Corresponds to the OpenType hhea table LineGap field. ‘Typographic line gap. Negative LineGap values are treated as zero in Windows 3.1, System 6, and System 7.’

underlineThicknessinteger or float

Underline thickness value. Corresponds to the Type 1/CFF/post table UnderlineThickness field. Default is 50.

underlinePositioninteger or float

Underline position value. Corresponds to the Type 1/CFF/post table UnderlinePosition field. Default is –100.

### Related Topics

Font Info