## Presentation Device Driver Reference for OS/2

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### FOCAMETRICS Field - yMaxBaselineExt

yMaxBaselineExt (SHORT) Maximum baseline extent.

The maximum vertical space occupied by the font, in world coordinate units. This space is the sum of yMaxAscender and yMaxDescender if both are positive. It is also the sum of yInternalLeading and yEmHeight.

One possible line spacing can be computed by adding yMaxBaselineExt to yInternalLeading. Such a line spacing, however, would be dependent on the glyph set included in the font. If a new version of the font is made available with new glyphs, then it is possible that this value will change because one of the new glyphs has gone above the previous yMaxAscender or below the previous yMaxDescender. More sophisticated applications will base their line spacing on the point size (yEmHeight) of the font, which is an invariant of the font, multiplied by some factor (for example, 120%), plus any external leading.

yMaxBaselineExt may exceed yEmHeight.