PC engine duo Din 5 AV out

[chriscomputers]

I was wondering if anyone new what the +5V out on the pc engine duo Av cable was for? http://www.gamesx.com/avpinouts/duoav.htm
I have tapped video and audio here before without any issues not using the 5V and wanted to know if adding the +5V would improve things in any way.

[Duo_R]

For standard AV output, the 5+ doesn't do anything useful.

[chriscomputers]

Huh, so then what is the 5V even for? Why put it on there in the first place?

[Duo_R]

This has been somewhat discussed generally (not PC Engine specific) here:

http://nfggames.com/forum2/index.php?topic=734.0

+5v is available on the output to drive optional components (like RF switches) and is not needed for RGB, but GROUND is not an optional thing.

So perhaps there was a RF adapter for the Duo systems in Japan? I am pretty sure the U.S. didn't get those. Funny I never even considered a RF Adapter for Duo's, but if there was one it would have to go into the 5 din port (because the RF plug was removed in the Duo systems).