I</sub>| to include in the spin basis. 0 corresponds to only allowed EPR transitions, 1 includes additionally forbidden EPR transitions with |&Delta;m<sub>I</sub>|=1, etc. By default, all possible orders are included. By reducing <code>pImax</code>, the spin basis is truncated, and the calculation runs faster. For nitroxides, truncation to <code>Opt.pImax=1</code> often works and can yield spectra fairly close to the correct one. Truncation to <code>Opt.pImax=0</code> rarely works and is generally not advis