NST_NEST_LEVEL   1273 ext/mbstring/oniguruma/regparse.c     NBACKREF(node).state |= NST_NEST_LEVEL;
NST_NEST_LEVEL    172 ext/mbstring/oniguruma/regparse.h #define IS_BACKREF_NEST_LEVEL(bn)      (((bn)->state & NST_NEST_LEVEL) != 0)