Yeah, I parse those right now for the heading/position information. Which is completely annoying - it's in the ACARS format, which FSACARS/Xacars both use, I think FSPax does too, but IMO it's totally stupid to have that format to be parsed by a script. I mean, I understand they want to "emulate" what's used in real-world, but those are sent straight to printers, and are looked at by people for the information. It's a complete pain to parse and if something changes the entire format needs to be changed. /End rant
But, I'm not sure what you mean by defined, do you mean added into the log? Those are only sent with status messages, so there's no "log" that's kept (which is another weird thing, he goes through that effort to put it into the status message, there's no PIREP at that point), but then completely omits that log on PIREP time