Logic Pro time and key signature overview
Time and key signatures are global events that affect all tracks in a project. When you create a new project, you can set the time and key signature in the Project Chooser. You can view time and key signatures in the Signature track, the Signature List, and the Score Editor, and add and edit signature changes in a variety of ways.
The initial time signature and key signature are project properties. For information on setting the initial time and key signature, see Logic Pro project properties overview.
When Show Advanced Tools is selected in the Advanced preferences pane, the Signature track and Signature List are available so that you can create time and key signature changes.
Time signatures
Time signatures determine the number of beats in each bar (as shown in the ruler), and so define the editing grid in the Tracks area and the time-based editors (including the Audio Track Editor, Piano Roll Editor, and Step Editor). Time signature changes do not affect the playback of audio or MIDI regions.
In addition to the ruler, time signatures affect the score display. All functions that rely on the chosen time signature and bar positions (such as MIDI metronome click or Transform window functions) are affected if bar positions are used to restrict a function to a certain part of the project.
Key signatures
When you create a project, the key signature defaults to C major, unless you choose a different key signature. The initial key signature affects the playback of Apple Loops in the project. Key signature changes affect the display of MIDI notes in the Score Editor, but do not have an effect on MIDI playback.
You can add any number of key signature changes to a project. When you add a key signature change, it changes the key from the insertion point forward, until the next key signature change is reached.
You can store up to nine signature sets, which are reflected in the Signature track, Signature List, and Signature window.