Call it a joke. That one's MrVacBob's. I've put some of my own in Kareha, but it up to you to figure them out.
That's a pretty good idea, I think. Would be easier if one saved some metadata, but quite possible to do anyway. Hard to correctly parse references to range and such, though. One could maybe even add a link somewhere in each post to that.
I've been thinking of more extensions to that. The only useful one that I can think of is 'qX', which would display every post with an anchor to X. That would be kind of slow, though.