Setting PWM_OUT in new air frame configuration

I need a push in the right direction with regards to making a new airframe config.

After setting mixers, I see that you need to specify the outputs to drive/activate (ie. set PWM_OUT 1234). I would just like to clarify that this is turning on the PWM outputs specified, and whether or not I would need use different syntax to activate PWM out on the aux channels. My mixer has Pass throughs from the radio on both the MAIN5 and AUX4 outputs. I basically just need to know what the function of “PWM_OUT 1234” in more detail.

Apologies if this seems like an obvious question, but I couldn’t seem to find much detail in the documentation