Please give me an overview of VESA’s Display Port 1.4a

What is the difference between Display Port 1.4a and Display Port 1.3a? What is Multi-SST operation which is added on Display Port 1.4a? What is Display Stream Compression (DSC) and why is it used? Does it reduce power consumption, screen thickness, and allow for greater display flexibility? How is the segmented panel display designed? Thank You
