[CQ-Contest] Rules ARRL contest

[Peter Voelpel]

Looking into the rules for the ARRL contest it seems that there is no slot
for single op/single band "assisted".

3.1. Single Operator: 
3.1 2. Single Band. 
3.1.2.1. A participant may submit only one single band entry. If contacts
are made on other bands, the log file must clearly be marked as Single Band
in the header of the Cabrillo file. 
3.1.2.2. The same callsign may not be used by a different operator(s) to
generate additional single band entries. 
3.2. Single Operator Assisted. 
3.3. Multioperator: 
3.3.1. Single Transmitter. 

A friend of mine participated single band 20m CW and used the cluster.
What will be correct for his entry?
SO/SB, SO/SB assisted or M/S?

Also interesting for me, as I will do SB 20m on the weekend.
It would be my disadvantage if the competition is using the cluster. 

73
Peter