Number of active lines - 405 line system.

[Jac Janssen]

Found in a 1947 French book:
   

So it the French norm is quite flexible...
Number of lines between 440 and 455, 10 to 15 lines sync per frame.

Picture of the only 441 line set I have (Same chassis as the Philips TX390A and TX402A), here working @ 441 lines:
   

Jac