DTW import OCRD DiscRel or DscntRel

What is the difference between the fields DscntRel and DiscRel in the OCRD Table ?

In my query from OCRD I get different values for these fields (H, L) , but I cannot find the field DscntRel in the application-screens.

I want to Update the field DiscRel in the OCRD table but it is not available in the DTW Template for OCRD.

The system is SAP Business One 9.1 PL 7