Märklin-M series HO gauge track is designed specifically for AC powered, effectively three-rail Märklin layouts. It is only compatible with Märklin-K HO track (the track may be joined through a transition section), and the newly announced Märklin-C track. The Märklin-M track library even includes components of the older 'Modelle' track produced in the 1950's that is the precursor of the current M track.The table and image below show the components in the RR-Track Märklin-M HO track library.
The current v5 release build is 4.60.005. If yours predates this, visit our updates page and download the latest release.