The Prefixes DA...DM are valid from January
1949 until September 1973 for the common DXCC GERMANY.
(includes East- and West-Germany, GDR and FRG).
>From 1952 until 1979 "DM" was the mandatory prefix
for radioamateurs in East-Germany.
September 17th 1973 the GDR became a Member of the
United Nations. From that day until December 31th 1979
the prefix DM/DT counted for a new DXCC-country in the DXCC-List.
since 1980, as a political mark off, GDR changed the
prefixes DM / DT into the new prefixes Y2...Y9.
| DM2AGH | = | Y21GH |
| DM2EFG | = | Y25FG |
ITU
connoisseur Y2 - Y9
| Y21A - Y29Z | Relay station |
| Y31A - Y39Z | Contestteam |
| Y41A - Y49Z | Beacon transmitter |
| Y61A - Y69Z | Round saying station |
| Y2Ø - Y9Ø | Specialstation |
| Y21AA - Y28ZZ | Private station |
| Y29AA - Y29ZZ | Foreigner |
| Y31AA - Y99ZZ | Club station |
The last letter designated the district
| Rostock | A and U |
| Schwerin | B |
| Neubrandenburg | C |
| Potsdam | D and P |
| Frankfurt/O. | E |
| Cottbus | F and X |
| Magdeburg | G and W |
| Halle | H and V |
| Gera | J and Y |
| Suhl | K |
| Dreden | L and R |
| Leipzig | M and S |
| Karl-Marx-Stadt | N and T |
| Berlin | O |
also the next to last letter had its meaning
| A | Training station e.g.: Y64AF |
| B - Y | user at clubstation e.g.: Y33TA |
| Z | clubstations leader e.g.: Y38ZG |
Thanks DH5MM for info.