is mentioned by

Thm* x,y:T. x before y  nil  False	[nil_before]
Thm* x:T, L:T List. [x / L]  nil  False	[cons_sublist_nil]
Thm* x:T. (x  nil)  False	[nil_member]

In prior sections: core bool 1

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