Yes...here is a file describing the format... http://gps.chrisb.org/download/test_img.mp.txt
there are some interresting fields...

;RoadClass=dbf field name - importance of the road, 4 is most important road, 0 is least important road
;OneWay=dbf field
;Toll=dbf field
;VEHICLEE=dbf field - if set to true (or '1') then no emergency allowed on road
;VEHICLED=dbf field - no delivery
;VEHICLEC=dbf field - no car
;VEHICLEB=dbf field - no bus
;VEHICLET=dbf field - no taxi
;VEHICLEP=dbf field - no pedestrian
;VEHICLEI=dbf field - no bicycle
;VEHICLER=dbf field - no truck
;############

Marius