I think the word is actually spelled "purlin," and normally refers to framing members bridging laterally across roof trusses, rafters, or wall posts or studs.
You say (in the other question) that the slope is consistent, i.e. the floor is still planar, just not a level plane. This means the method suggested by shirlock homes in your other question shouldn't be too difficult; certainly a lot easier than the other options you mentioned.
If the slope is across 10 feet, and the outer edge is 1" lower than the inner edge, you'd start by ripping a 1" strip off the edge of a piece of 2-by lumber, so you'll have a strip that's 1" x 1.5". Attach that to the existing subfloor at the outer edge. Now say you've decided to put these shims every 12", that means you'll end up with 10 of them across the 10' dimension of your room, and each one will need to be 1/10" shorter than the last one so that you end up at zero right where the room meets the house. So rip your next one to 0.9" thick, or about 29/32", and attach it parallel to the first one, 12" away from it. Next one will be 0.8" or 13/16", and you'll attach it 24" away from the first one. Then just keep going until your last shim is 0.1" or 3/32" thick, and it will be about 12" from the inner wall of the room.
Once you've installed these shims, their top surfaces will form a flat level plane onto which you can attach your new subfloor. Your finished floor will be higher with this method (at the threshold it'll be equal to the thickness of your new subfloor plus the thickness of your new flooring material, and at the outer wall it'll be one inch thicker than that), but if that works in your situation I think this is a great solution.