Is it possible to kern two different scripts to the same punctuation mark/symbol?
T (Latin T)
Τ (Greek Tau – marked with a dot)
If there is an equal sign or a hyphen between them, it seems that kerning is only applied to the first script present in the sequence.
OpenType shaping happens on runs of charters with the same script, language and direction, so you can’t apply features across scripts. Common characters like equal sign will take the script of the previous character (usually), so it goes with the Latin T in the first word, and the Greek Tau gets in a run of its own and each processed separately.
Is a way to give priority to the second script so that the kerning is, at least, applied to that script instead?
Perhaps through creating a localised version of the punctuation mark with a distinct kerning group?
Script itemization is all up to the application and the font does not influence it (its uses Unicode Character properties), and its application basically does its own slightly incompatible thing as there is no documented standard for doing script itemization.
Interesting. Seems like this would be a commonly needed feature for various multi-script settings. Thank you for clarifying.
It is a know limitation of OpenType.