R. U. E. was one of the first acronyms I’ve learned on my journey within critique groups and reading writing related books. My old writings were full of explanation, but I thought it was my character’s thoughts. Albeit stating the obvious. After reading Self-Editing for Fiction Writers by Renni Browne & Dave King, I can catch those pesky unneeded expositions…most of the time. 🙂
Here are some blog posts on this topic.