AT&T MERLIN LEGEND Communications System Release 2.0 Maintenance And Troubleshooting Manual page 199

Unit Load Calculation Worksheet
7. Try to exchange modules between carriers to reduce the unit loads to 54.
(Remember that the 10OD, 400, 400 GS/LS/TTR, 800, and 800 GS/LS modules
have unit loads of 0.0.) Repeat Steps 1 through 6 to recalculate unit loads for
the new configuration.
If the exchange reduces the unit load to 54 or less, auxiliary power is
not required.
If the exchange does not reduce the unit load to 54 or less, auxiliary
power is required. Continue to Step 8.
NOTE:
Empty slots are not permitted between modules.
B-6 Unit Load Worksheet