Open/Close MIDI Insert 14 Plug-in Window of focused Track

Opens (closes) the 14th MIDI Insert plug-in. That’s an awful lot of MIDI inserts on a channel.

Use MIDI plug-ins in Logic Pro — Apple Support

MIDI plug-ins are inserted in software instrument channel strips and process or generate MIDI data—played from a MIDI region or a MIDI keyboard—in real time. Included are the Arpeggiator, Chord Trigger, and Modulator, along with plug-ins for transposition, randomization and other processing. Scripter enables you to create your own MIDI processing and generation scripts.

MIDI plug-ins are connected in series before the audio path of a software instrument channel strip.

MIDI plug-ins have a MIDI input, the MIDI processor, and a MIDI output. The output signals sent from MIDI plug-ins are standard MIDI events such as MIDI note or controller messages.