[en] Projects to produce and store anti p's and to accelerate anti p's and p's together in the same large ring are underway at CERN and FNAL. The goal is to achieve anti pp collisions with a luminosity L approximately 10³⁰ cm^-2 sec^-1 by perhaps 1980. These experiments predate any similar effort at ISABELLE by at least four years, so it is necessary to plan an ISABELLE project which will have significantly higher luminosity. A lower bound L = 10³¹ cm^-2 sec^-1 has been rather arbitrarily chosen. The basic numbers which enter into the luminosity calculations for the CERN and FNAL proposals are presented and are compared with what could be achieved at ISABELLE under ideal conditions