=item *
-C<RXf_SPLIT> and C<RXf_SKIPWHITE> are no longer used. They are now
-#defined as 0.
-
-=item *
-
The new C<RXf_MODIFIES_VARS> flag can be set by custom regular expression
engines to indicate that the execution of the regular expression may cause
variables to be modified. This lets C<s///> know to skip certain