Fs2004 Flight Plan File Description

Does anyone have the key to the various fields in a .pln file? When I open the file in Notepad, I can figure out most of what's in there, but some of the fields delimited by commas aren't obvious. For instance, theres a value right after the equals sign on the waypoint line; I've seen values of K5 and K6. And the waypoints ID's are listed twice - why? So if you can shed any light on the file structure for me, I would greatly appreciate it. The web didn't seem to have an answer.