Could I turn off the RF OUTPUT of 2955B with GPIB commands?

As you know,I got a project that need to control Marconi Instrument-Radio conmunication test set 2955B by computer,I download its 《Programmer Guide》 from here.but soon I got another problem:It seems that 2955B do not have any GPIB command to turn off its RF output in RX TEST mod,you can set RF Modulation off/on by GPIB command but not RF OUTPUT.

I also try to change its TEST MOD from RX TEST to TX TEST,but It seems no good enough to my project,there is a "ON/OFF" key on 2955B' s front panel,and you can turn off/on its RF OUTPUT by press "IN/OFF"key manually,In my opinion,if you can do something manually,you also can do the samething by GPIB commands.is that right?

I have sent an E-Mail to Marconi many weeks ago,but nothing back,so may be somebody here can help me about this problem,thank you!

I' don't know Marconi 2955B but in my experience i've seen often, inside instruments, some "soft" functions available via GPIB only or via keyboard only.

Try this:
1) looking and analyzing the language style, try to imagine or guess the sintax.

2) If possible, set out power to the lowest possible

3) if possible switch an internal relay (say RF path)

Thanks a lot,sergio mariotti.I have got the answer from www.aeroflex.com.
RF Output Off:RG NF0
RF Output on: RG NF1
Mod On:SM NF1
Mod Off:SM NF0
It very strange that the commands above can not find out in its GBIP OPERATION manual,and in its GBIP OPERATION manual,the command to turn off/on modulation is "SM MD0/SM MD1",and it work very well too.
thank you very much!