IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html
At:
sublist filter3 1. T : Type
2. T List
3. u : T 4. v : T List
5. L2:T List, P:(T). L2 filter(P;v) L2v & (xL2.P(x))
6. T List
P:(T).
nil if P(u) [u / filter(P;v)] else filter(P;v) fi