Sorry Gandalf, already implemented and appears to be working fine.
If changing it to a "_+_" is preferred for a sense of clarity, I can easily change the tag.
The following test file...
hdENDO2_A_U_OR_S_L_N_FST_WST_SWP_
...was successfully placed in a province of terrain type forest and size large. Will need to do more testing, but it could have been placed in any size province that contained any of the three tagged terrain types (forest, waste or swamp).
After I have had a chance to further stress test this, I will release the next update which will also include another serious bug fix involving pattern recognition and province placement. As with all things random, they can be some of the hardest critters to stumble upon. Illwinter certainly has my sympathies. I can't imagine trying to pinpoint things that can creep up in a piece of programming with the size and complexity of Dom3.