I've recently discovered a great little trick that's helped me take it even further - defining the proof as a variable as well.
So just two additional lines...
At the beginning:
set @proof = "whatever"
At the end:
set @proof = concat(@proof, " | " , @subject)
Then, when you use the UI to send a proof (you are using a UI, right?), you just change @subject to @proof.
It's simple, but by making it a consistent part of my process, it's saved me a lot of time and I'm far less likely to send unmarked proofs for review.