Rational Rhapsody DiffMerge always reports logical differences, while it might ignore graphical differences (see Suppressing graphical differences).
The following figure shows a partial view of the Dishwasher Cycle sequence diagram for the Dishwasher sample project provided with the IBM Rational Rhapsody product. Notice the location of evStart() before setup(). For aesthetic reasons, you could reposition evStart() (for example, move it down slightly so that it does not touch the partition line) but leave it still above the position of setup() and this movement is ignored by Rational Rhapsody DiffMerge because it does not affect the logic of the model.

In this example, notice that evStart() has been moved after setup(). This change has an effect on the logic of the model.

The following figure shows in Rational Rhapsody DiffMerge a comparison of the sequence diagrams shown in Example 1a (Left Value column) and 1b (Right Value column) in base-aware mode (Base Value column). As you can see, the logical difference is noted in the Right Value column.
