General AutoControl IIIB Question

[N293WK]

Having never seen the IIIB used in real life, I'm not exactly sure how it's supposed to work now that I think about it. My understanding was as follows, hopefully someone can clarify whether that is right or if I am wrong:

• If the HDG switch is off, the plane will maintain the bank being commanded by the roll knob, no matter what is selected by the coupler selector.

• If the HDG switch is on, the plane will bank to turn toward the selected course, heading, or navaid, whichever is selected by the coupler selector.

So for example, HDG switch off but coupler selector on NAV, the plane should ignore the nav and just fly at whatever bank is commanded by the roll knob.