What is "32GB post RTS"?

I read this in Dell XPS 15 2 in 1 at RAM Specification on

http://ift.tt/2Es4po1

8GB-16GB Dual Channel DDR4 at 2400MHz (On Board)
32GB post RTS

What is 32GB post RTS mean?

from Windows Central Forums http://ift.tt/2FiKtsE
via IFTTT