Documentation on ToProto() methods?

I see complete documentation of the Isaac protos themselves but not of the functions I keep seeing to fill out the protos (ToProto())

Is there anywhere that documents how this/these functions work?

I have been following the CAP’N’PROTO docs on packing protos but it would appear I’m missing some built-in functions Isaac has for packing related protos.

Thank you,
TravisM