I am looking at this:
http://docs.oasis-open.org/xliff/xliff-core/v2.1/xliff-core-v2.1.html#dir
The possible values are lrt, rtl, and auto
(with auto "determined heuristically, based on the first strong directional
character in scope, see UAX #9").
That is the same as the HTML dir attribute
https://www.w3.org/TR/2014/REC-html5-20141028/dom.html#the-dir-attribute
But that is not enough, because the direction based on the first char
results in bad rendering at times.
So the HTML standard added <bdi> and <bdo>
And also CSS needed to add even more control, with unicode-bidi:
https://www.w3.org/TR/CSS2/visuren.html#direction
The values in the CSS2 standard seem to be normal, embed, bidi-override,
inherit
But more are coming: normal, embed, isolate, bidi-override,
isolate-override, plaintext
(https://www.w3.org/TR/css-writing-modes-3/#unicode-bidi)
Mozilla and Chrome (and probably others will follow) already support these
values:
https://developer.mozilla.org/en-US/docs/Web/CSS/unicode-bidi
Chrome also supports "initial" (I don't check about Firefox)
So the proposed values for dir seem insufficient.
Kind of a pity to release something that is already outdated, without
learning from what others did...