REG_ESUBREG       100 ext/mbstring/oniguruma/regposix.c     { ONIGERR_TOO_BIG_BACKREF_NUMBER,                     REG_ESUBREG },
REG_ESUBREG       101 ext/mbstring/oniguruma/regposix.c     { ONIGERR_INVALID_BACKREF,                            REG_ESUBREG },
REG_ESUBREG        89 ext/pcre/pcrelib/pcreposix.c   REG_ESUBREG, /* reference to non-existent subpattern */