[78-L] Master Records prefix?

[Bryan Wright]

I've noticed that several ARC labels of the late 1930s attach a letter  
prefix to the catalogue numbers of recordings produced by Irving  
Mills's Master Records. For example, Conqueror discs of the late '30s  
normally have 4-digit catalogue numbers with no prefix or suffix (e.g.  
"9193"), but a Conqueror record derived from a Master master has a "c"  
prefix (e.g. "c9089"). I've seen this on Vocalion records too, with a  
"v" prefix. I have a few purple OKehs from Master, but they do not  
have any special letter prefix. Since the sides originating with  
Master already say something to that effect on the label, why the  
extra catalogue prefix? It seems redundant and perhaps even confusing.  
Was the prefix letter to make them stand out more in the company's own  
listings to perhaps facilitate easier royalty payments? Just curious.

Bryan W.