IC,
Don't know if this is what you mean but I came across a reference to a DME based Landing System (DLS) in a 1978 copy of the Manual of Avionics by Brian Kendal. Apparently this was (West) Germany's proposal for a MLS. It didn't make it to the final stage of the selection procedure, and a Google search only produced one hit - the meaning of the abbreviation DLS.
Regards,
Simtech