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The stand-alone hardware mapping is different from the software mapping as additional functions are available while using software which are not available for stand-alone mode. As such, the engineers felt it was best to have the layout for software match the layout of the other controllers in the DDJ family so users would be comfortable moving between the DDJ and XDJ with rekordbox, or if they were using the RX2 as a stand-alone unit, the labels would indicate the functions of those controls.
You can find a diagram here to help you master the product.