A character attribute (Character panel menu with the East Asian options;
`text.setFormat` / `text.setRangeStyle {proportionalMetrics}`), saved only
when on. In horizontal type it applies `palt`; vertical type sets as before
until the vertical shaping change (`vpal`) follows.
Line-end Punctuation Half Width takes nothing more off the punctuation
`palt` re-spaced (the flush opening bracket, consecutive punctuation, the
line-end half width): the segment is shaped once more without `palt`, and
the glyphs whose advance differs are marked. Punctuation the font leaves
full width is trimmed as before. SVG writes `"palt" 1` with the
character's other features.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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