%CALCULATE{formula}% variable is handled by the SpreadSheetPlugin. Over 100 functions are available, such as $ABS(), $EXACT(), $EXISTS(), $GET()/$SET(), $IF(), $LOG(), $LOWER(), $PERCENTILE(), $TIME(), $VALUE().
%CALC{formula}%
%CALC{$EXISTS(Web.SomeTopic)}% returns 1 if the topic exists
%CALC{$UPPER(Collaboration)}% returns COLLABORATION
$LEFT() or $T(). Use CALC instead.