First, consider a very simple 1-channel UBV photometer. Let us assume a rather minimal instrument: no cooling or temperature regulation, and simple DC photometry. This resembles the instrument with which the UBV system was first set up. Here is the table:
Table: Instrument table file for a simple photometer
As there is only one detector, we need not include the NDETUSED column.
Table: Instrument table file for a typical modern photometer