Please consult the manual of Regexp::Common for a general description
of the works of this interface.
Do not use this module directly, but load it via Regexp::Common.
Returns a pattern that matches an American Social Security Number (SSN).
SSNs consist of three groups of numbers, separated by a hypen (-).
This pattern only checks for a valid structure, that is, it validates
whether a number is valid SSN, was a valid SSN, or maybe a valid SSN
in the future. There are almost a billion possible SSNs, and about
400 million are in use, or have been in use.
If -sep=P is specified, the pattern P is used as the
separator between the groups of numbers.
Under -keep (see Regexp::Common):
captures the entire SSN.
captures the first group of digits (the area number).
captures the second group of digits (the group number).
captures the third group of digits (the serial number).
This software is Copyright (c) 2001 - 2009, Damian Conway and Abigail.
This module is free software, and maybe used under any of the following
1) The Perl Artistic License. See the file COPYRIGHT.AL.
2) The Perl Artistic License 2.0. See the file COPYRIGHT.AL2.
3) The BSD Licence. See the file COPYRIGHT.BSD.
4) The MIT Licence. See the file COPYRIGHT.MIT.