Grammar question: "As per: John"—how is this supposed to be used?

Factual Questions
1

At some of my places of employment, I see fellow employees post a new policy or order that comes from a supervisor or some boss—they’ll write (for instance), “Do not move this chair. As per Rita (the boss).” Or, “As per John: This order is due tomorrow.”

Or whatever. What the hell does this mean, “As per”? I know my grammar is not stellar, but it seems like the ones who most often write “As per” are no grammar geniuses themselves (having never seen a word ending in “s” that didn’t require an apostrophe, etc. etc.). Or maybe I’m completely clueless. It wouldn’t be the first time.

I am sure this “As per” trend has some basis from somewhere. And who knows, it might be perfectly correct. But I don’t understand what the hell it is, or how it is supposed to be used, or anything. (Oh, I understand that it is supposed to mean, “According to John” or “Rita has made the announcement that we should do it this way”, but I don’t know how all of that translates to “As per”.)

Have I been living under a rock? Is this a commonly used (and correctly used) term?

2

Commonly used? Yes. Correctly used? Almost never.

3

The word per has taken on many meanings over the years, one of which is “according to”. The OED has a citation from 1818 where the meaning is “as laid down by (by a judge)”, so this sense goes back a little. It’s not an uncommon usage, though it’s probably localized in settings where the usage is reinforced (like a particulary company). I’m not sure where the “as” came from since it isn’t needed. It may be that people were familiar with “as per usual”, where, again, the “as” isn’t necessary, but it’s fairly common.

4

Thanks, guys!

I find it a bit irritating, I must admit. I understood “per” (though I don’t use that myself when I am writing up a note or memo) but the “as” had me stumped.