Regarding expansion memory?

The Tyros 5 User Manual Page 108 states:

"In the Tyros5, one socket is available"

As the expansion memory is available for T4 and T5 in 512MB and 1024MB versions does this mean that the T5 slot as supplied is is normally empty? Alternatively is there a 512MB module installed which would require to be discarded if 1024MB was required?

Ian