In the FACTEX procedure, the MAXCLEAR option has been added to the MODEL statement for SAS/QC 9.3. The MAXCLEAR option requests "a design that maximizes the number of clear interactions, those which are not aliased with any other effects that are either required to be estimable or assumed to be nonnegligible." In the context of resolution 4 designs, a MaxClear design maximizes the number of two-factor interactions that are unaliased with any other interaction. See the section MaxClear Designs for details.