the distance that the font extends above the baseline.
Note that this is not always exactly equal to the maximum
of the extents of all the glyphs in the font, but rather
is picked to express the font designer's intent as to
how the font should align with elements above it.
the distance that the font extends above the baseline. Note that this is not always exactly equal to the maximum of the extents of all the glyphs in the font, but rather is picked to express the font designer's intent as to how the font should align with elements above it.