= Ascender
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{wiki}
= Ascender
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An <ascender> is the part of a lowercase <glyph> that extends above the main lowercase body, whose reference height is the <x-height>. Familiar examples occur in “b”, “d” and “k”. It is a feature of a particular drawn form, rather than a promise that every <glyph> in the <font> reaches the same height.<A Glossary of Typographic Terms by Adobe>[Entry ascender]{ref}
In a hypothetical <computer font>, put the <text baseline> at $y=0$, the <x-height> at 450 <font units> and the top of a chosen <ascender> at 730 <font units>. That part extends 280 <font units> above the lowercase reference. With 1000 <font units> per <em> and a scale of 20 <pixels per em>, the corresponding ideal heights above the <text baseline> are 9 and 14.6 <pixels>.
This local geometry is distinct from the global <font ascent> used by a text-layout system. That metric can also accommodate accents or other tall forms. <Glyph positioning> must preserve the chosen <text baseline> while allowing these different <bounding boxes>; simply aligning the tops of all <glyphs> would change the intended alignment.
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