Buddy Emmons is largely responsible for the design of the C6th copedent. A Jerry Byrd disciple, Buddy instructed Shot Jackson to put a C6th tuning on the back neck of his guitar. He specified the changes of the 8th pedal to reflect Byrd’s C6/A7 tuning, and the 5th and 6th pedals to get the most common bar slants heard in Byrd’s playing. (Bob White is credited with the standard P7 changes.)
By the 1970’s, most D-10 steel guitars had pedals 4 through 8 and RKL set up exactly like Buddy’s. When he changed his 1st string from G to D, legions of players and builders followed his lead. Many D-10s do not include the left knee levers, but Buddy’s configuration of them is considered to be “the standard”.
Sometimes Buddy raised the 6th string E to F on P4 instead of the the standard A to B changes. It’s a popular alternative. In an online conversation, he wrote, “My road Legrande has the As to Bs and my house guitar has the middle E to F, so I don’t have a preference between the two.”
See also: Buddy Emmons E9th Copedent