It's labeled "In RC6", but it's not mentioned in the owner's manual (though it is depicted on the hookup diagrams)
It is mentioned in the featue list of the promotional leaflet (but not in the main manual), only as an "RC6 Control Bus". Googling that term only returns a couple of pages of spec lists quoting that exact line. Googling "RC6" by itself returns mostly references to a Philips region code hack. The old DVD+RW.org forums appear to be a lost cause (I don't recall it ever being mentioned, and I've been reading that forum since the DVDR985 was a new model), and looking up the term "orange" in this forum's search function brings up only one post with no mention of that connector.
Googling "orange RCA" connector shows that this color is usually for a coaxial digital input/output. My cable box, a Scientific Atlanta 4200, has a digital audio out (black RCA jack, tho') and this would be useful in freeing up an audio input (dubbing from a VCR) if I could use it, since my EXT1/2 IN is already occupied by the stereo audio output of that same cable box, and I'd like to avoid cluttering up the front-panel input like I've done with the VCR (three game consoles through a 4-way selector).
But that designation "IN RC6" bothers me. The optical/coaxial digital outputs on this unit are labeled as digital outputs, and I'm thinking that the orange connector on the 985 is some Philips-specific oddity that has no real end-user purpose.
So anyone have any other insights?