SYSML21 — Multiple issues with swimlanes graphical notation productions

1. The perform-actions-swimlanes production does not appear to be used anywhere.
2. The swimlane production only appears to support vertical swimlanes. i.e., with the action flow displayed below the head rather than to the right of it. Horizontal swimlanes should also be supported.
3. There is no production for the <<performer>> keyword in the head of a swimlane. The appropriate production appears to be Usage-name-compartment (which is missing, as was noted in SYSML21-251), but this name should probably be changed to be more specific to this usage, e.g., swimlane-name-compartment or performer-name-compartment to be consistent with the names of other similar productions.
4. The note "Note. All swimlanes are attached to each other on vertical edges and aligned along the top and bottom horizontal edges." in 8.2.3.17 does not appear to be followed by the examples of swimlanes that appear in Table 15.
5. The swimlanes production have squared (right-angled) corners, but rounded corners appear in the examples in Table 15.