21. A computer program product, encoded on a machine-readable storage device, configured to cause one or more data processing apparatus to perform operations comprising: receiving a genre classification for a document, the genre classification comprising multiple terms and corresponding scores, each score for a term indicating a confidence level for the term with respect to the document; accessing a stored document control policy ontology, the document control policy ontology comprising a hierarchy of nodes that represent document genres and have corresponding document control policies; identifying an entry point node in the hierarchy of nodes of the document control policy ontology by successively comparing the multiple terms in the genre classification with the nodes in the document control policy ontology in order of increasing hierarchical position of the terms until either a matching node in the ontology is found or the term in the highest hierarchical position of the multiple terms is reached and no matching node is found in which case a document control policy corresponding to a root node is used the identifying comprising, when the document control policy ontology has an underlying classification structure different from a classification structure used for determining the genre classification, identifying a correlation between the different classification structures; assessing a confidence level for applicability of the entry point node based at least in part upon at least one of the scores; inferencing within the document control policy ontology to find a document control policy more conservative than the policy corresponding to the entry point node, the inferencing comprising selecting a parent node of the entry point node in the document control policy ontology to stand in for the entry point node if the assessed confidence level for applicability of the entry point node falls below a threshold, the parent node inheriting at least one document control policy derived from at least the entry point node; and recommending at least one document control policy to govern access to the document based on the identified entry point node or the selected parent node in the document control policy ontology.
21. A computer program product, encoded on a machine-readable storage device, configured to cause one or more data processing apparatus to perform operations comprising: receiving a genre classification for a document, the genre classification comprising multiple terms and corresponding scores, each score for a term indicating a confidence level for the term with respect to the document; accessing a stored document control policy ontology, the document control policy ontology comprising a hierarchy of nodes that represent document genres and have corresponding document control policies; identifying an entry point node in the hierarchy of nodes of the document control policy ontology by successively comparing the multiple terms in the genre classification with the nodes in the document control policy ontology in order of increasing hierarchical position of the terms until either a matching node in the ontology is found or the term in the highest hierarchical position of the multiple terms is reached and no matching node is found in which case a document control policy corresponding to a root node is used the identifying comprising, when the document control policy ontology has an underlying classification structure different from a classification structure used for determining the genre classification, identifying a correlation between the different classification structures; assessing a confidence level for applicability of the entry point node based at least in part upon at least one of the scores; inferencing within the document control policy ontology to find a document control policy more conservative than the policy corresponding to the entry point node, the inferencing comprising selecting a parent node of the entry point node in the document control policy ontology to stand in for the entry point node if the assessed confidence level for applicability of the entry point node falls below a threshold, the parent node inheriting at least one document control policy derived from at least the entry point node; and recommending at least one document control policy to govern access to the document based on the identified entry point node or the selected parent node in the document control policy ontology. 22. The computer program product of claim 21 , wherein the determining comprises classifying the document using a document genre ontology comprising a hierarchical knowledge structure containing a vocabulary of terms and concepts, and inference chains representing interrelationships between the vocabulary terms and concepts, for document genre classification; the genre classification comprises a subset of the inference chains; and the identifying comprises checking terms associated with levels higher than a lowest level of respective ones of the subset of inference chains.