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+SYNOPSIS
+        Henry Spencer Regular Expressions
+
+
+DESCRIPTION
+        This document describes the regular expressions supported by the
+        implementation by Henry Spencer (the traditional package for
+        LPMud).
+
+
+OPTIONS
+        The following bitflag options modify the behaviour of the
+        regular expressions - both interpretation and actual matching.
+
+        The efuns may understand additional options.
+
+          RE_EXCOMPATIBLE
+
+        If this bit is set, the pattern is interpreted as the UNIX ed
+        editor would do it: () match literally, and the \( \) group
+        expressions.
+
+
+REGULAR EXPRESSION DETAILS
+        A regular expression is a pattern that is matched against  a
+        subject string from left to right. Most characters stand for
+        themselves in a pattern, and match the corresponding charac-
+        ters in the subject. As a trivial example, the pattern
+
+          The quick brown fox
+
+        matches a portion of a subject string that is  identical  to
+        itself.  The  power  of  regular  expressions comes from the
+        ability to include alternatives and repetitions in the  pat-
+        tern.  These  are encoded in the pattern by the use of meta-
+        characters, which do not stand for  themselves  but  instead
+        are interpreted in some special way.
+
+        There are two different sets of meta-characters: those  that
+        are  recognized anywhere in the pattern except within square
+        brackets, and those that are recognized in square  brackets.
+        Outside square brackets, the meta-characters are as follows:
+
+          .       Match any character.
+
+          ^       Match begin of line.
+
+          $       Match end of line.
+
+          \<      Match begin of word.
+
+          \>      Match end of word.
+
+          \B      not at edge of a word (supposed to be like the emacs
+                  compatibility one in gnu egrep)
+
+          x|y     Match regexp x or regexp y.
+
+          ()      Match enclosed regexp like a 'simple' one (unless
+                  RE_EXCOMPATIBLE is set).
+
+          x*      Match any number (0 or more) of regexp x.
+
+          x+      Match any number (1 or more) of regexp x.
+
+          [..]    Match one of the characters enclosed.
+
+          [^ ..]  Match none of the characters enclosed. The .. are to
+                  replaced by single characters or character ranges:
+
+          [abc]   matches a, b or c.
+
+          [ab0-9] matches a, b or any digit.
+
+          [^a-z]  does not match any lowercase character.
+
+          \c      match character c even if it's one of the special
+                  characters.
+
+
+NOTES
+        The \< and \> metacharacters from Henry Spencers package
+        are not available in PCRE, but can be emulate with \b,
+        as required, also in conjunction with \W or \w.
+
+        In LDMud, backtracks are limited by the EVAL_COST runtime
+        limit, to avoid freezing the driver with a match
+        like regexp(({"=XX==================="}), "X(.+)+X").
+
+
+AUTHOR
+        Mark H. Colburn, NAPS International (mark@jhereg.mn.org)
+        Henry Spencer, University of Torronto (henry@utzoo.edu)
+        Joern Rennecke
+        Ian Phillipps
+
+
+SEE ALSO
+        regexp(C), pcre(C)