
Bounce Extensions settings in Logic Pro for Mac
When Enable Complete Features is selected in Advanced settings, the Bounce Extensions pane is available.
Bounce Extensions settings let you set the bounce extension and the surround format. The Bounce Extensions pane consists of the following settings:

Stereo
Left and Right fields: Sets the bounce extension for each audio file when bouncing in split format. You can change the extension by typing in the text field.
Surround
“Show as” pop-up menu: Choose a surround format to determine which of the 17 fields, representing the speaker positions, become active in the Bounce Extensions pane. The fields for speaker positions that are not available for the selected surround format are dimmed. See Overview of surround formats.
Initialize button: Resets the bounce extensions to their default values.
Surround extensions fields: Determine the extensions that are appended to audio filenames when bouncing in surround format. You can change the extension by typing in the text field. The extensions also determine the channel assignment when importing split surround files.