[XDJ-RX2] In shortcut menu, what does the ''Matching'' button do?

In the shortcut menu, there is a greyed out (inactive) button that says ''Matching''. I have tried many approaches, but I can't find it to work, nor do I know what function it holds.

The manual of this product does not contain any information about this function.

Could anyone explain its function and how I can enable it?

Regards,

Gido