Description: The object specifies the number of an ipv6 advanced ACL rule. If the number specified has been assigned to an ACL rule, the new rule will overwrite the old one, which is equal to editing the old rule. If the number is not assigned, the system will define a rule with the number and insert it to the place corresponding to its number. If no number is specified, the system will define a rule, assign a number to it and add it into the ACL. It will be placed at the end of the ACL when configuration sequence is adopted; otherwise, it will be placed based on the 'Depth-first' principle. When ACL rules are following the 'Depth-first' principle, the number of an ACL rule must be given 0 ,but it will be assigned automatically;otherwise,this rule will not be created.