-The default value of {\it base} $0$ is special and means that the usual rules
-of {\tt C} numbers are applied: if the number starts with {\tt 0x} it is
-considered to be in base $16$, if it starts with {\tt 0} - in base $8$ and in
-base $10$ otherwise.
+The value of {\it base} must be comprised between $2$ and $36$, inclusive, or
+be a special value $0$ which means that the usual rules of {\tt C} numbers are
+applied: if the number starts with {\tt 0x} it is considered to be in base
+$16$, if it starts with {\tt 0} - in base $8$ and in base $10$ otherwise. Note
+that you may not want to specify the base $0$ if you are parsing the numbers
+which may have leading zeroes as they can yield unexpected (to the user not
+familiar with C) results.