OfficeScan comes with a set of predefined expressions. These expressions cannot be modified or deleted.
OfficeScan verifies these expressions using pattern matching and mathematical equations. After OfficeScan matches potentially sensitive data with an expression, the data may also undergo additional verification checks.
For a complete list of predefined expressions, see http://docs.trendmicro.com/en-us/enterprise/data-protection-reference-documents.aspx.