3. The method of claim 1 , wherein the rule indicates that access to the requested document portion is denied responsive to the data describing past accesses indicating that access was provided to all document portions other than the requested document portion.
1. A computer-implemented method for controlling access to a portion of a document, the document comprising a plurality of portions, the method performed by at least one processor, the method comprising: receiving a request to access the document portion; identifying a variable accessibility rule associated with the requested document portion; evaluating the rule based on data describing past accesses of other ones of the plurality of document portions; determining whether to provide access to the requested document portion responsive to the evaluation of the rule; and responding to the request based on the determination.