Techniques for collaborating on a spreadsheet file by client computers in real time are disclosed herein. In particular, a revision manager module is preferably provided with a host machine which receives updates from the client computers, processes such updates, and then applies them to the spreadsheet file. Additionally, a technique is described for handling updates sent to the revision manager by clients simultaneously or near simultaneously. In this case, the revision manager determines whether the updates to the spreadsheet file are transformable or able to be merged. If so, the updates are combined into the spreadsheet file and applied thereto. If the updates are not transformable, the revision manager confirms that all clients have received all previous updates before applying the non-transformable update to the spreadsheet file.