I've been working on a Go-based Monero library and for the MixRing of a RCT, we need the previous outpoints that are being mixed in. It's easy enough to grab those output keys and put them in the destination. The mask, however, is computed with the commitment. What commitment is that referring to? How do I compute it?
Pointers to code in the monero-project/monero codebase would be very helpful.