Add, subtract, multiply, divide, modulo
-B<SIN, COS, LOG, EXP>
+B<SIN, COS, LOG, EXP, SQRT>
-Sine, cosine (input in radians), log, exp (natural logarithm)
+Sine, cosine (input in radians), log, exp (natural logarithm), square root
B<ATAN>
Z<>
+=item Ordering Operations
+
+B<SORT, REV>
+
+Pop one element from the stack. This is the I<count> of items to be sorted
+(or reversed). The top I<count> of the remaining elements are then sorted
+(or reversed) in place on the stack.
+
+Example: C<CDEF:x=v1,v2,v3,v4,v5,v6,6,SORT,POP,5,REV,POP,+,+,+,4,/> will
+compute the average of the values v1..v6 after removing the smallest and
+largest.
+
=item Special values
B<UNKN>