The ComboBox built-in plug-in was added in Unify v1.2.0. Unlike all the other plug-ins bundled with Unify, it neither produces or processes either sound or MIDI by itself, but instead provides an environment in which you can connect any number of plug-in instances in arbitrary ways, and thus escape the constraints of Unify's linear-chain layer architecture. It's also unique in that you can use a ComboBox instance in any of Unify's three types of plug-in slots: Instrument, MIDI-effect, and Audio-effect. (MIDI Monitor is the only other plug-in which can sensibly be used in all three slot types.)

When you first load an instance of ComboBox, the user interface will look like this:

The four boxes labeled MIDI Input, Audio Input, MIDI Output, and Audio Output represent not plug-ins, but the inputs and outputs of ComboBox itself. The keyhole-shaped red and green protrusions are called “pins”; these represen