Difference Between M1 and ML markings on receiver

I am currently looking at possibly purchasing a Saginaw M1 carbine on gunbroker.com  At the top of the receiver, it is marked US carbine Cal 30 ML instead of US Carbine cal 30 M1.  I did some research and as best as I could find the ML was common to companies like IAI that produced commercial, non USGI versions of the carbine.  However as far as I know Saginaw never made weapons commercially, so why the ML on the top of the receiver, and does it in fact mean a non-government issue weapon?

The "ML" receiver marking is seen on IAI and Kahr (Auto-Ordnance) commercial M1 Carbines. As Lupus Dei mentioned, a photo would help.

David Albert
dalbert@sturmgewehr.com