D.2. TrueType Collections

A TrueType collection (TTC) [258] is a file with the extension .ttc that contains a set of TrueType fonts that share some tables. The header of a file of this sort is also a TrueType table, named ttcf. What is interesting about a TTC relative to the individual TTFs that it contains is the fact that the TTFs can share a large part of their resources. For example, recall that the Japanese language has four scripts: the kanji () ideographs, of Chinese origin; the hiragana () and katakana () syllabaries; and the "modified" Latin script roma j i. Thus we can easily imagine Japanese fonts that share the kanji but contain different kana or different Latin letters.[D-5] Given that the kanji make up perhaps 95 to 99 percent of the total volume of the glyph descriptions, it would be strictly redundant to have the same kanji in multiple Japanese fonts. In a TTC, we can set things up so that the same table of glyphs (for all the glyphs, including the different versions of kana) is used in different ways, which is equivalent to providing several TrueType fonts.

[D-5] We have already seen this sort of situation during the rearrangement of a CID font (§C.7.3). It shows that ...

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