DL92 is also known as 3S4 and N17 and CV820
DF91 is also know as 1T4 and CV1971
DF904 is also known as 1U4
The CV nomenclature is a British Military designation.
If you see tubes marked with "JAN" then these also are military tubes, "JAN" is normally found on US tubes but can be found on other countries tubes. "JAN" stands for Joint Army and Navy.
Hope that helps and welcome!
Edited by ianmedium - 7/19/13 at 9:56am