#define NREFFA 69 /* 0x45 Match already matched string, folded using unicode rules for non-utf8, no mixing ASCII, non-ASCII */
#define LONGJMP 70 /* 0x46 Jump far away. */
#define BRANCHJ 71 /* 0x47 BRANCH with long offset. */
-#define IFMATCH 72 /* 0x48 Succeeds if the following matches. */
-#define UNLESSM 73 /* 0x49 Fails if the following matches. */
+#define IFMATCH 72 /* 0x48 Succeeds if the following matches; non-zero flags "f" means lookbehind assertion starting "f" characters before current */
+#define UNLESSM 73 /* 0x49 Fails if the following matches; non-zero flags "f" means lookbehind assertion starting "f" characters before current */
#define SUSPEND 74 /* 0x4a "Independent" sub-RE. */
#define IFTHEN 75 /* 0x4b Switch, should be preceded by switcher. */
#define GROUPP 76 /* 0x4c Whether the group matched. */