Host could ask to open the Plug-in about box. The host could call it with onlyCheck set to true for testing support of open AboutBox. Return kResultFalse means not supported function.
Host could ask to open the Plug-in help (could be: opening a PDF document or link to a web page). The host could call it with onlyCheck set to true for testing support of open Help. Return kResultFalse means not supported function.
Host could set the Knob Mode for the Plug-in. Return kResultFalse means not supported mode. \see KnobModes.