17. The method of claim 16 , wherein responding to the request based on the determination comprises responsive to determining to provide access to the requested document portion, presenting the part of the document that matches the search query.
16. 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, the document portion containing a part of the document that matches a search query; 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.