The international efficiency marking protocol for external power supplies is a system used by manufacturers to identify what efficiency level the supply meets. The efficiency level is marked on the supply’s label by a roman numeral that corresponds to a specific efficiency level. This makes it easy for users to quickly identify the efficiency level of a particular external power supply. The current protocol is for power supply manufacturers to indicate compliance by placing a Roman numeral based on the efficiency level on the power supply label as specified by the International Efficiency Marking Protocol for External Power Supplies Version 3.0, updated in September 2013. This latest version of the Protocol provides additional flexibility on where the marking may be placed.