Open Score Editor… ⌘5
Opens the Score Editor window. You can have multiple Score Editor windows open, each with their own view.
The Score Editor displays MIDI regions on software instrument (and external MIDI instrument) tracks as music notation, including notes, rests, key and time signature, and clef signs. Bar lines show the division between measures. Gaps between regions are filled in to display a continuous staff. If the track contains software instrument Apple Loops, notation is displayed for each loop iteration, but only the original region of the loop can be edited.