Next Sequence in Main Window

Something I don't quite understand yet is when I am in the Main Screen, and I hit WINDOW with the sequence name highlighted, I'm able to change the name of the sequence but there also is a "Next sequence:" option that can be turned on or off. What does this exactly do when you choose ON or OFF? I am in free JJOS 3.16.

http://www7a.biglobe.ne.jp/~mpc1000/version3e.htm

Hallelujah! I'm not sure where that's found on his website but thanks for the link.