The name of this label is tentative. It never had a proper name and most releases were shrouded in mystery. Since all releases feature an "M" (sometimes highly stylized), it is also often referred to as M. The name "Maurizio" is used here in relation to the main artist on these (though also not credited).
The releases do not really have catalog numbers. For M4 to M7 the releases were numbered in their titles, so the catalog numbers are assigned after these titles (as can easily be seen below). The first three releases have their 'catalog numbers' assigned in order of appearance. The original EFA release of the CD didn't feature any catalog number besides the distributor's, as well, 'M-CD' is only given to fit it in with the rest.
Official catalog numbers can be found on the labels homepage, which (retrospect) refers to the label as M-Series.