The type design I'm currently working on has regular caps that serve as lead caps, swash caps, and a set of capitals designed to set for all cap settings.
I'm trying to figure out which feature tag to put these in. I had thought it would be good to use some sort of contextual feature so that if more than one cap were typed in a row the lead caps would be substituted by the all caps set. I also have ligatures designed for the all caps set. The all caps are just slightly shorter than lead caps so that they line up well, but they are not really small enough to declare as small caps, so I would be hesitant to use that tag even though it might logically serve the purpose.