Reply To: Kerning Options: Metric, Optical, Numeric, and Zero (0)

I continue to seek affirmation/veto of the descriptions contained in OP.
In the meanwhile, I’m perplexed: I’ve set a complex document to include only Optical kerning, then exported to idml. Upon opening the idml in cc2015 and in cc2018 there is significant conversion of the Optical to Zero kerning. Curiously, the resulting cc2015 and cc2018 PDFs are identical, confirmed using a pixel-level comparison tool. This leads me to believe that the change from Optical to Zero occurs when the idml is created, not in the conversion of idml to indd.