The Exception of 10.7.9.d. Overruns are also prohibited in hexes where Lingering Mud is in effect. Each ASP can participate in supplying units of only one attack. There is one exception to this principle. There is one exception governing Hill, Mountain and Alpine terrain.
Engineers can attack without using their special DRMs.
The note makes it sound like it is optional add support. If either DRM or support is used, they must be applied to the same hex. If possible both must be used. Use the same method for Optional VP Scoring based on step losses of certain unit types. Only one mission can be flown to a particular hex in any single phase.