In-plan Roth rollovers/conversions

I've been driving myself crazy on this. Question came up as to whether an in-plan Roth conversion/rollover could satisfy the RMD requirements. I know it can't, but I'm having a devil of a time finding "proof" - and I'm sure it is staring me in the face! I recalled that there was guidance a long time ago where it said that for 401(a) purposes, an in-plan rollover was not a "distribution." So I looked back at IRS Notice 2010-84, etc., etc., and while I found SOME of what I was looking for, I couldn't find anything that confirmed this head-on -  (or possibly my eyes scanned over it). Anyone recall the citation for this? There's ample IRS verbiage out there that addresses this in an IRA context, but seems to be a dearth of similar IRS publications answering this same question for designated Roth accounts.

Shoulda stayed in bed this morning...

RMD's are not eligible for rollover, ergo are not eligible for conversion/in-plan rollover either.

Thanks Lou. Yeah, I know RMD's are not eligible for rollover. The assertion was made that since the conversion is taxable, the taxable amount would represent a "distribution" from the plan. I know this is wrong - but this is the piece I'm trying to "prove" - that it is not, in fact, a distribution from the plan for 401(a) purposes.

Not a cite, but if that line of logic were accurate, there would be no such thing as an RMD from a non-converted Roth 401(k) elective deferral balance because the entire account would have been "distributed" (albeit a little bit at a time) immediately upon deferral. 

Or, for a more extreme example, a participant has a $100,000 pre-tax balance in 2021 and will reach 72 during 2022. If they do an in-plan conversion of all $100,000 during 2021, would this person take the position in 2022 that no RMD is ever required because the entire account had been distributed by 12/31/21? If so, not sure any cite will help. 

Ok, got it. Obvious brain cramps yesterday. Thanks to you both.