-i,j : local reference position index (de Bruijn's)
-k : sort index
-l : term degree
-m,n : reserved: future use
-o :
-p,q : global reference position
-r : reduction kind parameter (true = ordinary, false = extended)
-s : local dropping kind parameter (true = general, false = restricted)
-t,u : local reference position level (de Bruijn's) (RTM)
-v,w :
+i,j : local reference depth (de Bruijn's)
+k,l : global reference level
+m,n : iterations
+o : sort degree parameter (origin)
+p,q : binder polarity
+r :
+s : sort index
+t,u :
+v,w : local reference position level (de Bruijn's) (RTM)