Why are diff and merge files read-only?

[dan]

By default, the Vault client will invoke SourceGear's DiffMerge tool to not allow the user to modify the files in a diff, nor modify files in a merge other than the resulting merge, regardless of the read-write status of the underlying files. This is done so that files are not accidently changed by the user during a diff or merge.

To change this default behavior, go to the Vault client's Tools->Options->Diff/Merge pane, andremove the /ro1 and /ro2 arguments in the diff program and/or the /ro1 and /ro3 arguments in the merge tool. These are the arguments that cause the diff/merge program to treat the files as read-only, regardless of the actual read-write status of the file.

Note that without these arguments, the diff/merge tool will honor the actual read-write settings of the underlying file, and if the underlying file is set to read-only, the diff/merge will not allow that file to edited.