A number of different choices are possible on WFPC2 in order to approximate the Johnson-Cousins system often used in ground based observing. These choices differ in throughput, wavelength fidelity, color transformability, and cosmetics. The HST science program as a whole benefits if a standard set can be agreed upon by the community for broad band photometry. ... These filters form the basis for the WFPC2 broad band photometric system. ... Space Telescope Science Institute . ...