20. The system of claim 19 , the portion of the updated comment comprising at least some properties of the updated comment, including changed properties of the original comment.
19. A system comprising: a server device; a storage element coupled to the server device; and a client device communicatively coupled to the server device, at least one of the client device or the server device comprising a display, a processor-implemented comment management module, and a processor-implemented rendering module, the processor-implemented comment management module operable to receive an updated comment added to a document that updates an original comment stored in a collaboration comment repository, the original comment being stored in conjunction with a comment series identifier and a first comment differentiation identifier, the comment series identifier and the first comment differentiation identifier being independent of a document version associated with the document, to generate a second comment differentiation identifier to differentiate the updated comment from the original comment, to store at least a portion of the updated comment in the collaboration comment repository stored on the storage element, the updated comment being stored in conjunction with the comment series identifier and the second comment differentiation identifier, the updated comment and the original comment being different versions of a same comment, and to utilize a combination of the comment series identifier and one of the comment differentiation identifiers to uniquely identify a particular version of the same comment, and the processor-implemented rendering module to cause the display to display the particular version of the same comment in association with a time line of comments associated with a displayed document having a content portion and a comment portion, the time line including a first version indicator representing the original comment on a first part of the time line and a second version indicator representing the updated comment on a second part of the time line, and to display the original comment on the time line of comments without changing the content portion of the displayed document, responsive to a user selection of the time line.