In LD21, print the NET_DATA as shown below.  Check the response to the "FTOP" prompt - click the link below that matches your system setting.

>ld 21
PT1000

REQ: PRT
TYPE: NET
TYPE NET_DATA
CUST 0

TYPE NET_DATA
...(unrelated prompts not shown)

FTOP = FRES  
FTOP = TBFT  
FTOP = FTTB  
FTOP = FTLY  

...(unrelated prompts not shown)