Nothing in the rules will state "ACSSB is not allowed" or ACSSB is allowed". The rules give the technical parameters for signals on a band. Any more that meets those technical parameters - and is publicly documented - is permitted. ACSSB would seem to meet those requirements. 73 Dan Henderson, N1ND Regulatory Information Manager ARRL, the national association for Amateur Radio™ 860-594-0236 dhender...@arrl.org