Double-filters can be implemented by dragging an item to the Filter line twice. However, one deficiency to this method is that when applying multiple filters on one item, browse level settings are not effective; that is, the server values retrieved are not constrained by another filter on the same item, because both filters are defined using the same pool of server values. Nevertheless, an elegant solution to this issue is available through the use of the meta topic, which enables the administrator to establish filters at different logical levels.
Meta topics are logical views which overlay the original tables-and-joins model of a database. Items that display in meta topic view inherit any modifications made to the original items in the underlying physical topic view. In this instance, a fixed filter can be applied to the date item in the original database topic. Once a meta topic, which includes the date item, is created to serve as the user view of the Data Model, a variable filter is applied to the date item in the meta topic.
Since the fixed filter is applied to the original date item, the meta topic date item incorporates this filter transparently. The values excluded by the fixed filter are not associated within the new meta topic, and are not returned by the Show Value feature for fixed or variable filters applied to the new meta topic item. Note also that Filter Browse Level settings need not be modified under this scenario because the filters in question are applied to different logical layers.