Help with kerning groups and stylistic alternates issue

So far I’m really loving Glyphs, but the documentation is kind of thin. I’m not understanding how kerning groups are supposed to work (and the meaning of the little locks on the metrics hud).

Also, I’m having issues with the OpenType “salt” tag. Automatic generation doesn’t work at all. Manually including the feature in “aalt” and building the lookup table exports correctly, stylistic alternates don’t appear in the features pulldown in the text editor.

I’m just now working on an improved documentation.

All letters that have the same tag in the kerning group field will end up in the same kerning class. You may use the basic glyph name as tag, but also descriptive names like “round shapes”.

So all accented letters from the “A” get a “A” for both the left and right group tag. The “AE” gets an “A” for the left group and an “E” for the right side.

Kerning either between a kerning class or a glyph directly. (not like in FontLab, that the kerning classes are attached to the kerning of the key glyph.)

The lock icons indicate if there is a exception for that pair.
Example: you have typed “To”. Both glyph have kerning groups set. If you kern this pair, the kerning will be applied to the kerning class. Have a look at the kerning panel. you will see something like “@MM_L_T” and if you klick the triangle next to it it shoes “@MM_R_o” and the kerning value.
If you now type in “Tö” (the “ö” is part of the “o” group) the dieresis might collide with the T bar. You need an exception. place the cursor between the “T” and the “ö”. You see the glyph info box for the “odieresis”. Then click the left look icon and correct the kerning. If you now check the kerning panel, you see two entries in the “@MM_L_T” group. One for the T class with o class and one for the T class with the “odieresis” directly.

As fare as I know, the salt feature is not supported by InDesign and most other apps. So you have to use the ssXX features instead.