Developers in the team need to see the differences between an archived version of a unit and another version of the same unit that might need to be merged. To accomplish these tasks, they need to see the graphical differences between the two versions, as well as the differences in the code.
A IBM Rational Rhapsody® unit is any project or portion of a project that can be saved as a separate file. These are examples of Rational Rhapsody units with the file extensions for the unit types: