NST_NEST_LEVEL   1292 ext/mbstring/oniguruma/regparse.c     NBREF(node)->state |= NST_NEST_LEVEL;
NST_NEST_LEVEL    154 ext/mbstring/oniguruma/regparse.h #define IS_BACKREF_NEST_LEVEL(bn)      (((bn)->state & NST_NEST_LEVEL) != 0)