The underlying XML is fully documented. The binary LRF is not, but it's been documented by the people that first reverse engineered it. To see the XML documentation you need to sign up for a free account at prslabs.com.
The binary part is documented at
http://www.sven.de/librie/Librie/LrfFormat
and I am days away from releasing an open source cross platform LRS->LRF compiler which means all you really need to care about is the XML part.