Def ma-frame-compatible(A; B)
Def == kx:(KndId). 
Def == (kx  dom(1of(2of(2of(2of(2of(A))))))
Def == (
Def == (2of(kx)  dom(1of(2of(2of(2of(2of(2of(2of(A))))))))
Def == (
Def == (2of(kx)  dom(1of(2of(2of(2of(2of(2of(2of(B))))))))
Def == (
Def == (deq-member(KindDeq;1of(kx);1of(2of(2of(2of(2of(2of(2of(
Def == (deq-member(KindDeq;1of(kx);1of(B)))))))(2of(kx))))
Def == & (kx  dom(1of(2of(2of(2of(2of(B))))))
Def == & (
Def == & (2of(kx)  dom(1of(2of(2of(2of(2of(2of(2of(B))))))))
Def == & (
Def == & (2of(kx)  dom(1of(2of(2of(2of(2of(2of(2of(A))))))))
Def == & (
Def == & (deq-member(KindDeq;1of(kx);1of(2of(2of(2of(2of(2of(2of(
Def == & (deq-member(KindDeq;1of(kx);1of(A)))))))(2of(kx))))

is mentioned by

Def A ||+ B == A || B & ma-frame-compatible(A; B) & ma-sframe-compatible(A; B)

[ma-compat]

Try larger context: EventSystems IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html