From the DTML manual : variance-nnn : The variance of numeric values computed with a degrees of freedom equal to the (count - 1). variance-n-nnn : The variance of numeric values computed with a degrees of freedom equal to the count. standard-deviation-nnn : The standard deviation of numeric values computed with a degrees of freedom equal to the (count - 1). standard-deviation-n-nnn : The standard deviation of numeric values computed with a degrees of freedom equal to the count. So I try: <!--#var standard-deviation-EGO --> which works, however, <!--#var standard-deviation-2-EGO --> provides: Traceback (innermost last): File "<stdin>", line 1, in ? File "pedsys.py", line 218, in summary return HTML(html)(self) File "./DT_String.py", line 513, in __call__ File "/usr/pkg/zope/lib/python/DocumentTemplate/DT_In.py", line 678, in renderwob try: append(render(section, md)) KeyError: standard-deviation-2-EGO All statistics-n-nnn forms result in a key error regardless of how/ where I use them. Am I misreading the manual on how to use them? I'm running Zope 1.10.2 but I peeked at 1.11.0pr1 and saw that there have been no changes to DT_InSV.py between the two versions (1.10.2 and 1.11.0pr1). Thanks Kent