[Css-csts] Discrepancy in SpaceLinkDatUnit lower bound

[John Pietras]

Members of the CSTS WG,
Perhaps this is something that has already been recognized, but I will
raise it in case it has so far otherwise escaped detection.

There is a discrepancy in the lower bound of the SpaceLinkDataUnit type
definition in the various sections A2.1 SLE TRANSFER SERVICE--COMMON
TYPES: 
- In RAF-B-2, RCF-B-1, FSP-B-1, and ROCF-B-1, the lower bound is 4. 
- In CLTU-B-2, it is 7 (it was also 7 in both RAF-B-1 and CLTU-B-1).

I assume that the value was lowered to accommodate ROCF, but that the
change failed to be reflected in CLTU-B-2. 

Best regards,
John