Thank you so much to all reviewers for the comments.
1) Scripts like Mongolian and 'Phags Pa that are inherently vertical, but would (possibly) be rendered "stacked" horizontally with an upright instead of rotated orientation in the absence of cursive rendering. Maybe OC=VRS (Vertical script rotated or stacked horizontally)?
The question is valid and the model extensible, but the proposal aims to provide a default classification for vertical text layout. Nonetheless, it would be interesting to see if evidence of upright, disconnected Mongolian or 'Phags-pa in horizontal layout exists.
2) Scripts like Tibetan that are cursively joined and layed-out horizontally, but are rendered in vertical context upright, with the cursive breaks indicating a vertical line break. http://www.tibetan-calligraphy.com/tattoos/components/com_virtuemart/shop_image/product/Simple_vertical__4b64625d55d2a.gif
Would OC=SR cover this?
A specialized vertical text layout that stacks morphemes instead of glyph clusters is conceivable. The proposed property provides a classification which any generic vertical layout can use. With the proposed RS classification, a specialized layout could conceivably accomplish a more complex stacking either via a shaping system that produces larger glyph clusters or by another layout process. The inclusion of the tsheg is worth researching further for the more general case of punctuation marks such as the apostrophe (or even modifier letters) that can appear together with a preceding character as one cell in a vertically stacked layout. Thank you for providing the Tibetan sample.
Let's refer to this proposal as L2/02-012, since that's the L2 doc number for it.
The L2 document number is L2/12-102.
The "Wide ‘!’" should be FF01 and "Wide ‘"’" should be FF02.
Those two comments are indeed off by one table row. Thank you for pointing that out.
Why ‘°’ (U+00B0 DEGREE SIGN) is S (Stackable only)?
Why ‘±’ (U+00B1 PLUS-MINUS SIGN) is S (Stackable only)?
Why ‘〓’ (U+3013 GETA MARK) is TR (Transform Rotatable)
and ‘゠’ (U+30A0 KATAKANA-HIRAGANA DOUBLE HYPHEN) is TS (Transform Stackable)?
Thank you so much for the excellent feedback. Some property values were assigned based on evidence of attested usage, others were derived algorithmically from other UCD properties, such as General_Category or East_Asian_Width. As a result, some assignments need finer adjustment, and expert feedback such as this is most valuable. We will apply all of the suggested changes, except for the following, where further comments are sought:
- The box drawing pieces are a rather special category of symbols, in a way similar to arrows, which have their own class A. Rather than introducing a distinct class, the box drawing characters were assigned the value S because they are intended for compatibility with older mechanisms of character cell graphics, which can imply a specialized layout where the characters are individually picked for their 2D connectivity.
- Regarding the fractions, could you please provide samples where U+2044 and U+215F are used with superscripts and subscripts, if available?
I think the reviewers would benefit greatly if you provided the data part in a machine readable form.
I agree. Is it possible to post a data file? That helps the review at CSS WG a lot.
The data, although not in a machine readable format, is included in the proposal annex.