* compile to execute that permits the execute phase to run lots faster on
* simple cases. They are:
*
- * regstart sv that must begin a match; Nullch if none obvious
+ * regstart sv that must begin a match; NULL if none obvious
* reganch is the match anchored (at beginning-of-line only)?
* regmust string (pointer into program) that match must include, or NULL
* [regmust changed to SV* for bminstr()--law]