Definition restrict_sm mu (X:block -> bool) :=
match mu with
Build_SM_Injection locBSrc locBTgt pSrc pTgt local extBSrc extBTgt fSrc fTgt extern =>
Build_SM_Injection locBSrc locBTgt pSrc pTgt (restrict local X)
extBSrc extBTgt fSrc fTgt (restrict extern X)
end.

Lemma restrict_sm_extern: forall mu X,
extern_of (restrict_sm mu X) = restrict (extern_of mu) X.