AAT Font Quality Specification
System Requirements
(AAT) Recommended features
Although an AAT font can have minimal features beyond what a non-AAT
font contains and still require ATSUI to operate properly, this is what
Apple sees as a recommended minimum for a font to be considered an "AAT"
font.
Font size
The smaller a font's file size, the better. While there is no specific
size requirement, it will always be better to have a font that takes up
less memory and disk space. If all of the above recommendations are followed
for character mapping, point count conservation and instruction optimization,
a significant overall saving in size is possible.
(AAT) These small yet cumulative savings will become even more important
as fonts get larger numbers of glyphs in AAT and with variations.
Testing criteria
All data provided in the font should be as per the TrueType font specification.
The tool Font Validator, available from Apple, will verify and validate
the data. The font should not have any errors or warnings flagged by the
tests run by Font Validator. Other Apple tools like TrueEdit (font table
editor) and RoyalT ( font glyph editor) will let you correct these values
and ensure correct and accurate data in the font.
Required tables
All of the necessary tables as specified in the TrueType font specification
should be complete and accurate. All other auxiliary tables created and
used by tools that are not used by the system should be stripped from the
final release version of the font.
[NOTE] A reference version of
the font, with all tables intact, must always be saved against the need
to return to the font for revisions, corrections or additions at some later
date.
The minimum required tables for a TrueType font are indicated in table
4-1.
fig. 4-1 Required Tables.
[NOTE] Figure 4-1 shows the minimum required tables
for a functioning font. Other tables will be necessary to implement any
additional features. A description of all tables can be found in the TrueType
Font Format Specification (Chapter 6) at fonts.apple.com.
Operating systems
The fonts should be fully compatible with System 7 and following upgrades.
The fonts should be robust and should print without problems on printers
using QuickDraw, QuickDraw GX, and PostScript, and they must display correctly
on screen. The fonts should also be tested under 6.0.x systems using the
TrueType init, available from Apple.
All fonts should be fully compatible with, and run properly on all 68K
Macintoshes. However, the majority of the testing should concentrate on
the 68030 and 68040 machines. Similarly, the majority of testing should
be done on System 7 and 7.1 or later, with a small percentage on 6.0.x
systems.
Standard character sets
The minimum required glyph repertoire for Roman fonts has been upgraded
from the Apple 226+32 glyphs that has been the standard for TrueType fonts
in the past. This new standard applies to both AAT and non-AAT fonts, and
provides additional glyphs for non-English language localization. This
new standard is shown in appendix B.
This minimum glyph repertoire standard does not apply to ornament, dingbat
or specialty glyph fonts. The character sets for the non-Roman languages
can be found in the Guide to Macintosh Software Localization, chapter 13.
This minimum glyph repertoire standard also does not apply to CJK fonts,
which have their own minimum standards. There are a number of different
national standards for CJK fonts. Consult the Unicode Standard, volume
2, for details on the requirements and glyph repertoires for the various
CJK standards. See also: Chapter 2:
National standards.
Family naming conventions
In general, for non-AAT fonts, Apple ships four styles of a font: regular,
bold, italic and bold italic. If the 'fond' is built correctly, these styles
(the font subfamily name) will be added to the font family name appropriately,
in parenthesis, after the font name, when looked at in the System or Fonts
folder (e.g. "Times (bold, italic)"). Placing the font style
into the font name manually will cause duplicate naming and/or confusion
to the system and the user, as applications referring to these names will
not be able to determine font family relationships.
For non-AAT fonts, the family name is obtained from the 'fond', and
the style is obtained from the style bit in the 'fond'. Because of this,
the styles for non-AAT fonts are limited to the traditional four (regular,
bold, bold italic, italic). If more styles exist, they must be placed into
separate suitcases (such as Helvetica Black, which the system thinks of
as a 'regular' font, with a separate identity from the Helvetica family).
(AAT) For AAT fonts, the style naming conventions are different, because
more style options are available, and the style choices are more flexible.
The font name and style information are both obtained from the 'name' table,
from the family and sub-family name strings respectively. The sub-family
name can be anything desired (italic, bold, black, ornaments, zany, etc.)
However, to be backwards compatible with non-ATSUI systems, all AAT fonts
should have the appropriate name and style bit set in the 'fond', so that
the correct name and style (or best approximation of style) will display.
(AAT) Family names for AAT fonts should not differ from non-AAT fonts.
The use of any appendage to the font name, such as "AAT" (e.g.
"Helvetica AAT") is strongly discouraged.
Apple will provide detailed information describing the different name
strings, and copyright/trademark information, that are required for the
'name' table.
General compatibility
Fonts should behave correctly on a variety of standard Macintosh applications
including word processing, display, graphics, accounting, spreadsheets,
etc., both when displaying on screen and when printed.
Robustness
Instructions and outlines should not fail under transformations such
as rotation, skewing, perspective, stretching, wrapping (fitting to a curve),
etc. Deltas is an exception to this, because, although they will not work
under transformations, they must often be used when no other more robust
alternative exists.
Localization
Fonts should be localized for all intended markets; e.g., the 'name'
table should have all applicable translations. For more information on
what table and feature name translations are available, and in what languages,
see the Apple Font Feature Registry and the Guide to Macintosh Software
Localization.
Arleigh Movitz
The Apple Fonts Group
