Who Cites iseg?
iseg	Def l1  l2 == l:T List. l2 = (l1 @ l)
	Thm* T:Type, l1,l2:T List. l1  l2  Prop
append	Def as @ bs == Case of as; nil  bs ; a.as'  [a / (as' @ bs)]  (recursive)
	Thm* T:Type, as,bs:T List. (as @ bs)  T List

Syntax:

l1  l2

has structure:

iseg(T; l1; l2)

About: IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html