The PCRE (Perl Compatible Regular Expressions) library is included in NWC for use by the Find and Filtered Properties features. The easiest way to get started with using PCRE is to utilize the many web sites that cover the subject. For example:
PCRE License Compliance
The following section is for PCRE license compliance:
Regular expression support is provided by the PCRE library package, which is open source software, written by Philip Hazel, and copyright by the University of Cambridge, England.
The referenced ftp site for the PCRE source is identified in the license as:
NoteWorthy Software, Inc. has customized the included PCRE mechanism to protect against stack overflow. The modifications are similar to those found in later versions of the official PCRE distribution.