EH: the RW
Marinens Flyvevæsen designations of the time included the landing gear style, wing layout description, and type number. The former included F (
flyvebåd or flying boat); H (
hydroplan or floatplane); and L (
landfly or wheeled gear). Wing layouts were, obviously, B (
biplan) and M (
monoplan). Type numbers were rendered as Roman numerals.
The MF seems to have contracted descriptions (eg:
hydrobiplan) while the main aircraft maker, Orlogsvæft, broke these down with its initials as suffix (eg: OV-
hydro biplan). This is also shown in OV-J-01 which was the manufacturer's designation, not the potential end user's.
BTW, the Orlogsvæft's March 1938 H.M.III concept was basically for a H.M.II (Heinkel HE 8 replacement). The requirement was dropped when it was concluded that naval reconnaissance no longer dictated a float gear.
As Thiel said, the Dantorp was designated H.B.III. I presume that the H.B.IV was to be the undelivered Heinkel He-114s (the contract wasn't signed until 02 March 1940).
The OV-J-01 (for
Orlogsværftet Jager 01) project was proceeded with but the localled-made Fairey P.4/34 (L.M.I) had priority. With the OV-J-01 (aka
Marinejager) lagging, the MF ordered 12 interim Macchi C.200s from Italy. Since neither type was delivered, we can't be sure which design would have received the L.M.III designation (L.M.II being the KZ-II
Sport lightplane).
I have a soft spot for things Danish ... hope this nerdy diversion doesn't come off as too JMN-ish