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There is tables that explains which applications support different opentype features like this link:
In this table we see that all of the mentioned apps support the "standard ligatures" opentype feature.
but how would I know if I implement an GSUB LookupType 5 or 6 (Contextual substitution) in a standard ligatures it will be executed in those apps. I need a GSUB LookupType 5 or 6 to be executed by default in any application, so I think it's safe to put it in this feature and it will be executed in all of those apps, right?