NAMING CONVENTIONS FOR METAVARIABLES
A, B, C, D: term
+F,G : subset of subterms
H : transient premise
IH : inductive premise
M, N : term
P, Q : pointer tree
R : arbitrary relation
-T, U : arbitrary small type
+S : arbitrary small type
+T, U, V, W: subset of subterms
-c : pointer step
+a : arbitrary element
+b,c : boolean mark
d, e : variable reference level
+f : arbitrary function
h : relocation height
i, j : variable reference depth (de Bruijn index)
k : relocation height
l : arbitrary list
m, n : measures on terms
+o : pointer step
p, q : pointer
r, s : pointer sequence
-t, u : arbitrary element