AAT Font Quality Specification
Design Consistency
Serif/sans serif style maintained
The font should be designed so that consistency is maintained throughout
the typeface. For example, glyphs such as the trademark, registration,
and copyright symbols should be serifed designs in a serif font and sans
serifed in a sans serif font.
Italics
Angle consistency/ caret slope
When applicable, the italic angle of the font should be correctly specified.
This information is stored in the 'hhea' table, as two components, a rise
value (vertical axis) and a run value (horizontal axis).
(AAT) The resultant caret slope can be viewed most accurately in the
TrueEdit 'lcar' table editor. The italic angle should also be used for
the value of the slant ('slnt') font descriptor.
Which glyphs to italicize
The design characteristics should be maintained in all the different
styles of the font. Certain glyphs are not usually italicized. In an italic
font, these upright glyphs should be positioned to space correctly between
the italic glyphs. The slanting of these glyphs cannot be avoided in a
font that is obliqued on the fly by the computer (such as Helvetica), but
should not intentionally be slanted if it can be avoided. Only those glyphs
that are legally recognized symbols, with defined shapes (e.g. registration,
copyright, trademark, and the Apple icon) should never be obliqued.
There are two schools of thought about whether or not some glyphs (such
as the math operators) should be obliqued in an italic font. Except for
the glyphs that are legally recognized symbols, defined in the previous
paragraph, this is up to the discretion of the designer.
Drawn symbols
Greek symbols (e.g. Sigma, Pi, Omega, Delta) should be true to the style
of the font, and should not just be copied from the Symbol font. In general,
special glyphs and symbols should be the identical, except for positioning
within the advance width, for a regular and italic fonts, and the bold
and bold italic fonts.
Weight contrast
Keep family relationships in mind when instructing a font. A family
of fonts can be independently instructed in such a way that the regular
and bold weights are indistinguishable from each other at small sizes and
low resolutions (on screen). In some cases the bold weight can actually
look lighter than the regular. Provide contrast between weights at low
resolutions whenever possible, to avoid user confusion. The bold weight
must be at least as heavy, if not more heavy, than the regular weight.
Even if this cannot be done for all glyphs, doing it to as many glyphs
as possible will at least help a body of text look bolder when emboldened
by the user.
(AAT) Less can be done about this in variations fonts, because thickness
contrast between weights will be more subtle. However, variations fonts
will tend to have their various weights instructed at the same time, rather
than independently, so this problem should be addressable where possible
at the time of instructing.
Arleigh Movitz
The Apple Fonts Group
