Some definitions of interest.
gcd_p	Def GCD(a;b;y) == y | a & y | b & (z:. z | a & z | b  z | y)
	Thm* a,b,y:. GCD(a;b;y)  Prop
nat	Def  == {i:| 0i }
	Thm*   Type
le	Def AB == B<A
	Thm* i,j:. (ij)  Prop
not	Def A == A  False
	Thm* A:Prop. (A)  Prop

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