Lack of standardisation of variants

[r12a]

The lack of standardisation surrounding the outcome of using free variation selectors across fonts makes content authoring unreliable. In addition, the many rules needed to control automatic selection of appropriate glyph variants, particularly for the QA and GA letters, present a barrier to would-be font designers.

Experts from Mongolia and China are currently working with the Unicode Consortium in order to simplify and standardise the Mongolian encoding model in ways that will address this issue.

[r12a]

The first comment in this issue contains text that will automatically appear in the Mongolian gap-analysis document as a subsection with the same title as this issue. Any edits made to that comment will be immediately available in the document. Proposals for changes or discussion of the content can be made in comments below this point.

[lianghai]

The lack of standardisation surrounding the outcome of using free variation selectors across fonts makes content authoring unreliable. In addition, the many rules needed to control automatic selection of appropriate glyph variants, […]

This sounds a bit reversed.

The fundamental shaping logic of the Unicode Mongolian encoding is: a character relies on automatic contextual shaping to decide the actual variant; then an FVS is used when the automatic shaping fails.

So FVSes make a secondary (although last-resort) mechanism, while the automatic contextual shaping is the foundation and shouldn’t be “in addition” to the FVS mechanism.