Patent attributes
Provided are, among other things, systems, methods and techniques for determining applicability of a policy defined by reference to a source document. A first sketch that was generated based on content of the source document is obtained, and a matching criterion is defined based on the first sketch. Also obtained is a second sketch that was generated based on content of a potential target document. A determination is made as to whether the policy applies to the potential target document based on whether the second sketch satisfies the matching criterion and, if the policy applies, a notification regarding applicability of the policy automatically is provided and/or an action automatically is blocked so as to prevent a violation of the policy.