The $GID_DEPTH property, which is automatically created and set when a GROUPINGID command populates a grouping id relation, specifies the number of levels of grouping ids in the grouping id relation to which it is added.
You can not explicitly define a $GID_DEPTH property. Oracle OLAP automatically creates a $GID_DEPTH property on a grouping id relation when the execution of a GROUPIONGID command creates the relation.
$GID_DEPTH = intlevels
INTEGER value that specifies the number of levels of grouping ids.