Yes, it is somewhat undocumented but logical, if you see the layout of the global settings... that was the only place where they could add another setting (before they now invented the third row).
Has anybody cheked if this is now contained in the Global Settings sysex dump? I remember reporting a bug or two about the NRPNs for global settings not working properly, and the Arp Beat Sync not being reported at all. Its a bit of a shame as it makes setting up the device on a computer impossible, and sometimes when I am too confused I like to look at a screen to see what should be going on (e.g. Clock Sync, Local/On Off, Program Change settings etc.)