8. The non-transitory computer readable storage medium of claim 7 , electronic report further identifies each reference sheet name notation that refers to a primary sheet name notation that is not in the electronic index.
7. A non-transitory computer readable storage medium storing instructions that, when executed by a processor, are configured to cause the processor to perform operations comprising: receiving a plurality of digital pages having machine-encoded text, wherein the machine-encoded text of the plurality of digital pages includes a plurality of notations, including primary sheet name notations and reference sheet name notations; identifying each sheet name notations as one of a primary sheet name notation and a reference sheet name notation, wherein each reference sheet name notation refers to a primary sheet name notation on another of the plurality of digital pages; generating a digitally accessible electronic index in a non-transitory computer-readable medium that associates each identified primary sheet name notation with one of the plurality of digital pages, and associates each reference sheet name notation with (i) the digital page on which it is located and (ii) the primary sheet name notation to which it refers; and generating an electronic report of the electronic index that identifies each reference sheet name notations that refers to a primary sheet name notation, wherein the report of the electronic index includes at least one primary sheet name notation referred to by multiple reference sheet name notations on different digital pages, wherein the electronic report includes at least one primary sheet name notation referenced by at least two reference sheet name notations on different digital pages, and wherein the generated electronic index includes a first primary sheet name notation on a first digital page referred to by (1) a first reference sheet name notation on a second digital page and (2) a second reference sheet name notation on a third digital page.