Thanks so much Carl. Yes, it appears that R-872 is for bromine, the R-0003 for CL.

I see that all three numbers are listed multiple times with extra letters/numbers added, such as R-0003-A, R0003-A-24, R-0003-A144 etc. etc. When I drill down into each one I see it lists the same language, so I'm guessing that they are all the exact reagent, and that the different suffixes merely represent some type of cross-referencing.

There is one more thing you could help me with. I don't understand Step 1. of your instructions. It simply doesn't compute, i.e., what does it mean "For 1 drop = 0.2 ppm, use 25 mL sample. For 1 drop = 0.5 ppm, use 10 mL sample." I must not recall this from Ben's 2005 kit or we just didn't have the option. In any case, this will clearly become important because of the 'drop equivalence' in Step 4. Can you expound on for my brain block? Thanks again -