X 10.3.1: Logic Pro

: Introduced support for Audio Unit v3 specifications for virtual MIDI ports. Historical Context: The 10.3 Foundations

: Fixed a critical bug where moving regions could cause unexpected behavior or accidental deletions, particularly when using Track Alternatives . Logic Pro X 10.3.1

: This allowed users to create and switch between different versions of a track (regions and edits) without losing work. : Introduced support for Audio Unit v3 specifications

: A "flatter," cleaner design optimized for Retina displays with 24 additional track colors for better organization. : A "flatter," cleaner design optimized for Retina

To understand 10.3.1, you have to look at the massive 10.3 update it stabilized:

: Added the ability to share projects with sample rates other than 44.1kHz directly to GarageBand for iOS .

: Introduced the ability to apply effects plugins directly to a single audio region rather than an entire track.