REG_ESUBREG        51 ext/ereg/regex/regex.h #define	REG_ESUBREG	 6
REG_ESUBREG        51 ext/mbstring/oniguruma/onigposix.h #define REG_ESUBREG          6
REG_ESUBREG        89 ext/pcre/pcrelib/pcreposix.h REG_ESUBREG,     /* bad back reference */