14. The system of claim 12 , wherein the linkage metadata associates at least two fragments that are members of a set of fragments comprising the target fragment and at least one matching source fragment that have a same value for a metadata attribute.
12. A system comprising: a processor; and a computer readable storage medium having code executed by the processor for performing operations, the operations comprising: in response to a determination that a target fragment in a target document matches a source fragment in a source document, generating a linkage metadata for the target fragment, wherein the linkage metadata is generated for target fragments from the target document and source fragments from multiple source documents to provide information on how the target fragments in the target document relate to the source documents having matching source fragments, wherein the source documents have content to compare against received target documents.