Loading OSC integrated RGB file in Combine RGB Tool

Hi,

When loading an integrated OSC RGB file in the Combine RGB Tool (with one of the RGB formulas selected), the Chooser window allows you to load it three times, once each for Red, Green and Blue channels.  Does that Tool split out each channel from that OSC RGB file before loading it?  Or does it simply load the complete OSC file into each Red, Green and Blue channel?

Is it necessary to split out the Red, Green, and Blue channels and save them first with the Calibration Tab? And then load them individually in the Combine RGB Tool into their respective channels?

Thanks,

Jeff