Now suppose you have all the files set up to make MIDAS happy, and you are ready to plan an observing run. The proper distribution of extinction and standard stars was discussed by Young . The program is based on this discussion, but includes other considerations as well (such as the need to measure time-dependent extinction, and to measure instrumental zero-point drifts). It should help you get the right amount of good calibration data with a minimum of observing effort.
The command MAKE/PLAN will ask questions about what you are trying to do, and produces a schedule of observations that will meet your goals, if possible. If you are trying to do something impossible, it will tell you so, and offer suggestions. In general, if you follow the suggestions of the planning program, you will get the data you need -- assuming that the weather cooperates!
The planning program needs to know which photometric system you want to work in, and will try to supply appropriate standard stars. You can provide other table files of standard stars, if you wish; but be sure they really are on the same system as the built-in standards!