1. A method of displaying annotations created for different versions of a document comprising: determining, by operation of one or more processors, a family identifier associated with the document, having an initial version and one or more subsequent versions, wherein the family identifier is associated with the initial version of the document and with the one or more subsequent versions, and wherein each subsequent version of the document modifies textual content of the document relative to other versions; determining, by operation of the one or more processors, a version identifier associated with one of the versions of the document, wherein the version identifier provides an indication of either the initial version or a given one of the subsequent versions of the document; retrieving, from an annotation store, a set of one or more annotation records wherein each retrieved annotation record indicates the family identifier and the determined version identifier of the document displaying, for each annotation record with a version identifier matching the determined version identifier, an indication that annotation content is available for a text passage in the version of the document associated with the determined version identifier; retrieving, from the annotation store, at least a first annotation record, wherein the first annotation record has a version identifier that does not match the determined version identifier; upon determining that the first annotation record is associated with annotated content not present in the document associated with the determined version identifier, displaying an indication that annotated content is available for the text content not present in the document associated with the determined version identifier; upon request, displaying the annotation content associated with the first annotation along with annotated content from a version of the document associated with the first annotation; and selecting at least one annotation record with a matching family identifier but non-matching version identifier to associate with the determined version of the document.
2. The method of claim 1 , wherein the family identifier comprises a hash value generated from a SHA-1, MD5, or other hash algorithm.