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.
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. 20. The system of claim 12 , wherein the operations further comprise: adding the target document to a content database as a new source document; adding information on the target fragment to the content database as a new source fragment; and including information on the linkage metadata for the target fragment in linkage metadata for the new source fragment.