Re: [alreq] How are underlines positioned in Arabic text?

We discussed underline/overline methods on the 7 February 2017 weekly 
meeting.

Here's a summary:

1) Existing practices (meaning almost any handwriting, lithography, 
movable type, and traditional word processors) puts underline/overline
 below/above all glyph parts (letter parts and diacritics). Therefore,
 this is a desired behavior.

2) We will keep looking for other practices and will document when we 
have good evidence.

3) Based on the samples collected, looks like implementations need to 
find a better way of calculating a position for underline/overline 
based on font data. Most probably, it will use ascend and descend 
values for the positioning.

4) In any case, if the underline/overline collides with ink, the 
prefferred default behavior would be to skip the ink.

5) When skipping ink, it's also preferred to make sure the 
underline/overline drawing does NOT form a short pieces, which could 
be easily mistaken with dots or diacratics. To prevent this, the 
drawing can be skipped for parts with a short width.

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Received on Wednesday, 15 February 2017 09:43:51 UTC