I use three filters: V, B and I. I took images in each of these filters of M67 and used Tom Krajci's spreadsheet to analyze the data. I got lots of slopes, etc. Reading the Transforms-Sarty.pdf available from AAVSO I see three "cases" that might apply: BVI case, VI case and BV case. Which case should I use (or should I use more than one? - note that I would probably only use two of the three filters on any given target)?
Given that, how would I enter the respective values of Tv. Tvi, Tbv, and Tb as defined by Sarty?