[RTTY] Zone sent as letters?

[Phil Sussman]

I'm still a bit confused with USOS. I'm clear on the transmitting side.

On the receiving side, if USOS is engaged:

By convention, does the receiving software insert a shift-FIGS 
character when a space is detected after a number AND a shift-FIGS 
is not already in the data stream?

-or-

Is it assumed when USOS is engaged on the receiving side that
the transmitter (by default) already is using USOS.

-or- 

Is this a matter of the particular version of software being used
on the receive side?


So, if 599 03 CA is sent with USOS, what would a non-compliant
receiver decode .. I assume 599 PE CA .. correct?

I suppose the answer lies in what a receiver will decode if
USOS is OFF on the transmit side, but engaged (ON) on receive.

Thanks,

de Phil - N8PS