Comment (by Roland Haas):

Yes, MultiPatch_GetBoundarySpecification is the equivalent function in Llama.

However Llama’s function assumes to be called in SINGLEMAP mode (or more correctly it assumes being passed a “map” number) which is not available in LEVEL mode. See https://bitbucket.org/einsteintoolkit/tickets/issues/2288/leans-boundary-condition-setting-for-bssn#comment-58230040 for what I believe to be the correct behaviour. Unfortunately no code that I am aware of currently handles this correctly. Not even McLachlan or the original CTGamma code, so input from the Llama developers would be helpful.

--
Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2288/leans-boundary-condition-setting-for-bssn