When opening a project, ask whether current project should be closed checkbox: If selected and you open a new project before closing the old one, a dialog asks whether or not the current project should be closed. If the option is unselected, you aren’t asked and the current project remains open.
Export MIDI File command saves single MIDI region as format 0 checkbox: If only one MIDI region is selected when you choose File > Export > Selection as MIDI File, the contents of the region are saved in MIDI file type 0. This file type is compatible with every MIDI file player.
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Logic Pro User Guide: PDF