public void SetPairKerning( int characterIndex, int characterCount, bool hasPairKerning )
Pair kerning is a scheme where a table permutes every glyph against every other glyph, and each pair has an explicit kerning value defined. This option is desired for some legacy rendering. Non-pair-kerning is determined using a more sophisticated computation involving classes of glyphs, and this is the default.
Pair kerning isn't supported on all typefaces. If pair kerning is specified, but the typeface doesn't support it, non-pair-kerning will be used.