1. A computer-implemented method of enabling access control, the method comprising: automatically defining an access control statement, for determining authorization request validity using an authorization control engine for an asset, the access control statement comprising a first portion comprising one or more of a structural expression, and a conditional expression wherein the structural expression declares fixed relationships of the asset and a second portion comprising one or more of a classification expression comprising ontology expressions; and evaluating the first portion separately but simultaneously with the classification expression in the second portion of the access control statement, wherein the second portion uses an ontology engine.