Remote desktop RDP file settings list

Does anyone have a complete listing of the supported settings for the RDP
file of the new remote desktop client. Trying to get through htem through
trial and error but not havign much luck with settings such as span.
Somewhere detailed the setting span:i:1 for this one but this has not
materialised. Thought that maybe 'span monitors:i:1' may be ok as span
monitors got a hit in the the hex dump fo the executable.

Looking at auto configuring remote connnections with spanning enabled but
need to keep it backwards compatible so can not use an unsupported switch for
mstsc.

Cheers