Google Message Security for Google Apps Administration Guide - Manual (Page 251)

Content Manager 251
About the Social Security Numbers Lexicon
The Social Security Numbers lexicon is a predefined filter that finds U.S. social
security numbers in email messages. The following table describes how the
lexicon works:
Lexicon pattern
matching This lexicon matches sequences of 9 digits. The digits
in a valid sequence can be separated by spaces,
dashes, or periods. The following are examples of the
patterns this lexicon matches:
• nnn-nn-nnnn
• nnn nn nnnn
• nnn.nn.nnnn
• nnn-nn nnnn
The lexicon does not match different separators within
the group of digits. The following are examples of
patterns this lexicon does not match:
• nnn-nn.nnnn
• nnn.nn-nnnn
The lexicon does match a series of numbers followed
by a period. The following are examples of patterns
this lexicon does match:
• nnn-nn-nnnn.
• nnn.nn.nnnn.
The lexicon does not match a series of numbers
preceded by a period. The following are examples of
patterns this lexicon does not match:
• .nnn-nn-nnnn
• .nnn.nn.nnnn
The lexicon does not match a series of numbers
followed by a dash (-). The following are examples of
patterns this lexicon does not match:
• nnn-nn-nnnn-
• nnn.nn.nnnn-
The lexicon matches sequences of 9 digits that don’t
contain spaces or punctuation (in the pattern
nnnnnnnn ), if they occur within 4 words in the same
message as the text ssn or ss# or social security .