In MS SQLServer, it is a system generated value. From the BOL:
Is a data type that exposes automatically generated, unique binary numbers within a database. timestamp is generally used as a mechanism for version-stamping table rows.
In other databases, it's more like a DATETIME value would be. Anyhow, you can't have two timestamp columns in MS SQLServer because they would be identical with each other. This automatically tells me that the SQL script above is not related to MS.