Does FrameMaker support OpenType-Functionality

> FM currently doesn't support any specific OTF features, such as automatic ligatures.

After observing a combining diacritic fail in a recent test, I was wondering about that.

I'm guessing that except where FM has mapped its own legacy character (e.g. non-breaking hyphen, perhaps) to the Unicode equivalent, one cannot assume, without testing, that any of the following code points work as intended (not necessarily an exhaustive list): combining diacritics, invisible operators, LRE, LRM, LRO, NNBSP, RLE, RLM, RLO, PDF, WJ, ZWSP, ZWNJ, ZWJ

> You can only use glyphs via their unicode values.

It looks to me like you can only reliably use ordinary displayable glyphs (and only if the font populates the code points, of course). Any properties (such as format control) of the code point are ignored, other than legacy font metrics. You can at your own risk use combining characters, but only if you don't mind some risk that in some future FM release, or porting of the document to some other DTP system (or perhaps even rendering today in some workflows), the combiner collapses backward on top of the previous character.