CJKV Information Processing, 2nd Edition

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Chapter 6: Font Formats, Glyph Sets, and Font Tools

Ideographic Variation Sequences

To some extent, Ideographic Variation Sequences (IVSes, described at length in Chapter

3) handle what some believe to be gaiji by virtue of the fact that the IVS mechanism allows

otherwise unencoded, but somewhat standardized or common, variant forms of ideo-

graphs to be encoded through the use of a sequence of two Unicode code points, speci-

cally a Base Character followed by a Variation Selector. For some class of applications, if a

glyph is unencoded, it cannot be represented in the documents that it creates. As long as

the glyph in question is an ideograph, considered a variant form of an encoded character,

and falls under the ISO 10646 “Annex S” unication principles, the possibility of handling

it through the use of the IVS mechanism exists. Otherwise, the IVS mechanism would be

inappropriate.

For applications and environments that require a plain-text representation or environ-

ments in which only plain-text data can persist, such as the form elds of a PDF Form

or web browsers, IVSes can handle glyphs that would otherwise require gaiji treatment

in such situations. Also, IVSes provide a means of representing the identity of glyphs in

plain text, but fall short in solving the gaiji problem, because they do not add new glyphs

to existing fonts. Some applications, such as Adobe InDesign, ...