Okay, knowing where to look, I can see it was added to the versions in Cloaking and Hiding in the RMSS Spell Law. However, it also gives Displacement a type "F" for the Cloaking version, which would explain the "no RRs" bit. It doesn't explain why it wasn't just made type "E" like the other versions, so that the issue wouldn't arise. It's "E" for the Mystic's version in RMSS. Could you check the types for RMFRP, since you have that version and I do not? I suspect someone made the Cloaking version F (copying RM2), then realized that allowed RRs, so added that text. Then it got copied to the Mystic (which just referred to the Cloaking list in RM2), but someone corrected the spell type to match the Illusionist version and missed Cloaking and the added text. So, I don't think that the "no RRs" can be taken to match any intent to include base attack spells.
Unfortunately, I don't believe "attack" is a defined term in any version of RM, although if someone can find an official definition, that would help interpret intent.
Frankly, I don't think it works well to include spells that don't use an OB, because they don't "hit" or "miss". They either are resisted or they work. If Displacement affects them, it seems arbitrary that friendly spells (say a Blur) would not also have a chance to miss. There are also cases such as a Calm spell, which is not an attack in any conventional sense, but is a resistable spell that one generally does not want to be affected by.
If anyone has extensive experience using this spell in interaction with base attack spells, I would be interested in your experiences. I do think this could use clarification for RMU, and I would like to hear any relevant experiences to help decide how to do so.
