[css-ruby-1] The default ruby-position for vertical-lr text may not be over

[r12a]

4.1. Ruby Positioning: the ruby-position property
https://drafts.csswg.org/css-ruby-1/#rubypos

The TTML spec currently specifies that the default for text in Mongolian is to put annotations on the left side (the 'before' edge of the line box). CSS Ruby doesn't specifically say that, but implies it.

My understanding is that actually the default for Mongolian is more likely to be the right side, which i think is under. See an example and reasoning at w3c/mlreq#4

I think there should at least be a note in the CSS Ruby spec to warn developers that they can't just rely on abstract geometrical transformation theories to determine the location of the default placement for vertical-lr text.

[kojiishi]

over for Mongolian (vertical-lr) is on right. The over is line orientation relative. before is on left, since it's line progression relative.

[r12a]

Ah, i see. Thanks @kojiishi. I misinterpreted what over means. For the benefit of others reading this (and to remind myself in the future), over is described as

ruby text appears line-over the base

where line-over links to https://drafts.csswg.org/css-writing-modes-4/#line-over, where a distinction is made between before and over in the case of vertical-lr text.