LRT syntax reference?

Hi All

     I'm looking to find a good reference to Local Routing Table syntax.  I'd like to use a single LRT to do weighted routing, to a primary target first and if that primary target is unreachable, to a secondary target.  The LRT is necessary due to vendor requirements that we stamp outgoing calls with a reference for site identification, otherwise I could just use the basic routing functions.  I could use 2 LRT files one weighted more heavily than the other, but I'd like to find out if I can simplify.  I could also use a key replacement with the