Industry Rule 4. Numbering Advice Letters

For each type of service rendered, a Utility shall number its advice letters sequentially, beginning with No. 1, followed by a letter designating the type of service (E for electric, G for natural gas, H for heat, O for oil pipeline). A Utility may not reuse an advice letter number, regardless of whether the advice letter bearing that number was approved, withdrawn, or rejected. (See also General Rules 5.5, 5.6.)