39 Miss. Code. R. 1-24-110
In addition to the notice requirement placed upon the requestor herein, the Commission may give notice to any person that a declaratory opinion has been requested and may receive and consider data, facts, arguments and opinions from persons other than the requestor, including comments on whether a declaratory opinion should be issued.
The requestor, or his attorney, shall append to the request for a declaratory opinion a listing of all persons, with addresses, known to the requestor who may have an interest in the declaratory opinion sought to be issued, and shall mail a copy of the request to all such persons. If the requestor seeks a declaratory opinion as to the applicability of an order of the Commission entered in a contested case, the requestor shall serve a copy of the request upon all other parties in that case. If the requestor is a customer of a person or company regulated by the Commission which would be affected by the request, the requestor shall serve the person or company of which he is a customer. The requestor shall file a Certificate verifying that notice was properly provided pursuant to this rule and provide the date of such notice. The requestor or his attorney shall certify that a copy of the request was mailed to all such persons together with this statement: "Should you wish to participate in the proceedings of this request, or receive notice of such proceedings or the declaratory opinion issued as a result of this request, you should contact the Executive Secretary of the Commission within twenty days of the date of this request."
Any person or entity so served has ten (10) calendar days in which to file briefs in support of, or in opposition to the request for a declaratory opinion.
39 Miss. Code. R. 1-24-110