This is a descriptive addition to the lexicon rather than prescriptive, as is my wont. People are already using this on the internet, and I’d love to see it in common use because it’s very…well, useful. Google already has a definition cobbled together:
preposition /rā/ /rē/
In the matter of (used typically as the first word in the heading of an official document or to introduce a reference in an official letter)
– re: invoice 87
– I saw the deputy re the incident
Except they pronounce it “are ee”, which is retarded. Instead, it should be pronounced “ree”. And as a preposition, rather than a contraction of “regarding” or “respecting”, I insist that we drop the succeeding colon.