Quote - Quoting myself from my first reply up top:

 

I was going to refer LaurieA to that response, but I'm the sort of person who likes to test the truth of anything I say before I definitely say it, and since I'd never tried "Visible in camera" switched off on an ISF "fix" square, I wanted to see what would actually happen. Once I knew with absolute 100% certainty that it still worked, then I was happy to respond with an affirmative!

 

On the subject of ISF lights, I used to use your ISF shader set-up before Poser 8/PP2010 came along with in-built ISF. It was slightly more work to get the co-ordinates for the light position but it was definitely worth the extra few seconds compared to standard Poser lights at the time. The thing that I was looking into doing was changing it so that instead of always having an exponent of 2 (which is unrealistic if we're being really pedantic), it could be changed to have some other exponent in there. I was just about to start playing about with that idea when PoserPro 2010 came along and it got abandoned. I'm wondering if it's worth bringing that idea back up again, since neither pure inverse linear nor pure inverse square fall-off models any feasible light source in the real world.