1. A computer-implemented method, comprising: retrieving a document that includes for each page an area that is ignored by applications that process the document and that includes a different internal index set associated with each subset of pages of the document, wherein each different internal index set is associated with an area and stores indexes, and wherein each of the indexes consists of a name-value pair; and for each page in the document, determining whether the page is associated with an internal index set; and in response to determining that the page is associated with an internal index set, extracting one or more name-value pairs from the internal index set, wherein each of the one or more name-value pairs provides specific information about the document for use in identifying the document.