For vertical substitution to happen, the vertically rotated forms must exist in the font and must be indicated as such in the font's tables; otherwise, no characters are substituted. If the font supports the vertical substitution feature type, its default behavior is to perform such substitutions; you may either prevent the substitution or allow it to occur.
The Kana Spacing feature type is used to select widths specifically for Japanese Hiragana and Katakana characters. Table D-12 lists the selectors for this feature.
Table D-12 Feature selectors for the kKanaSpacingType feature type
