layout tables

Has anyone come up with a way to standardize on signaling that a table
is being used for layout purposes only?  When we run our documentation
through our accessibility checking utility, we have told folks to add a
null SUMMARY attribute to their tables, and our checking utility
recognizes this as a signal that the table need not be checked for
association between headers and cells, or for header markup itself.  Is
anyone else standardizing on this, or are folks using SUMMARY="This is a
layout table?"  Or some such variation?  It seems that the SUMMARY=""
makes sense in the same way that null ALT attributes work for decorative
graphics, no?

Is anyone interested in standardizing on such a thing, so that all ERTs
(Evaluation and Repair Tools) can be looking for the same thing?

Cheers,
-Kerstin Goldsmith