The tolerances on stray magnetic fields and on coupler asymmetry are calculated for moderate focusing, which corresponds to a low-energy cutoff of 1.4 Bev, and minimal focusing, where there is just enough admittance to transport the initial phase space of the beam. The tolerances obtained are compared with estimates of the magnitudes of various effects (variations of geomagnetic fields, etc.), and measures required to meet the tolerances are indicated. (D.C.W.)