From may 15th, 1965 to June 17th, 1966, they issued 300 different records (with an average of 500 copies each). DMF probably stands for Desmarets, Marie et Ferrant as per the 3 co-founders name and can sometimes be found as D.M.F. S.A. But other source says the acronym stands for Disque Microsillon Français.
To understand the catalogue number reference:
* 1st digit is for the genre (1: Classical; 2: Pop / Rock; 3: Poetry, 4: Various)
* 2nd digit is to designate the final number of the ongoing year when the record was recorded.
* 3rd digit is for the month the record was recorded.
* All subsequent digits display the number of the recording for a given year.
i.e: N° 25 665 is a Pop / Rock record released in June of 1965 and was the 65th to be released that year.
(Source: book 1958-1968 Les années rock en Haut-Normandie - Richard Louapre)