Try running your code with the ODS TRACE ON; statement just before your PROC MIXED.     The log will show that the "Solution for Fixed Effects" uses the Stat.Mixed.SolutionF template.  You can use PROC TEMPLATE to look at the source for the Stat.Mixed.SolutionF template.  The parent is the Stat.Mixed.tTests template.  DF uses the best4. format in the Stat.Mixed.tTests template.  ... View more