+.TP
+.B -funtyped-nil
+Adds a global named 'nil' which is of no type and can be assigned to
+anything. No typechecking will be performed on assignments. Assigning
+to it is forbidden, using it in any other kind of expression is also
+not allowed.
+.TP
+.B -fpermissive
+Various effects, usually to weaken some conditions.
+.RS
+.IP "with -funtyped-nil"
+Allow local variables named 'nil'. (This will not allow declaring a
+global of that name.)