The way VA defines The word "permanent" slightly differently.  For that matter, the word total doesn't mean total when discussing a disability. These are just terms to VA. There really isn't a protected rating. Any rating can be modified by VA at any time, depending on the circumstances.

How do you know if your benefit is P & T?

What is IU?

What is substantially gainful employment?

Are there any other eligibility requirements?

How is the way VA decides total disability different from other agencies?

TDIU awards may be permanent or they may be temporary.

If I get a 100% rating, should I continue fighting the VA for benefits?

SMC compensation