3. The method of claim 1 , further comprising: maintaining all versions of all comments associated with the document, including the original comment and the updated comment, in the collaboration comment repository.
1. A processor-implemented method comprising: receiving 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; generating a second comment differentiation identifier to differentiate the updated comment from the original comment; storing at least a portion of the updated comment in the collaboration comment repository, 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; utilizing a combination of the comment series identifier and one of the comment differentiation identifiers to uniquely identify a particular version of the same comment; displaying 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 displaying 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.