C6 tuning

C6 tuning is one of the most common tunings for steel guitar, both on single and multiple neck instruments. On a twin-neck, the most common set-up is C6 tuning on the near neck and E9 tuning on the far neck. 
On a six-string neck, for example, on lap steel guitar, C6 tuning is most usually C-E-G-A-C-E, bass to treble and going away from the player. Some other six-string C6 tunings are:
On an eight-string neck, for example, on a console steel guitar, popular C6 tunings are:
On a ten-string neck, typical of pedal steel guitars, a popular C6 tuning is C-F-A-C-E-G-A-C-E-G, adding two bass strings to the "high" eight-string tuning, or one string on either side of the F-bass "low" tuning. This is sometimes called the "Texas tuning". Another frequent variant is the reentrant C-F-A-C-E-G-A-C-E-D.
Kayton Roberts, a noted steel guitar player, used a modified C6 on his steel guitar's inside neck: A(low)-A-C#-E-G-A-C-E. On the outside neck he had F-C-Eb-G-F-A-C(though sometimes D)-F.