A query defines the data to be retrieved from the database. It consists of a source, a selection, detailed and summary filters, and a dimension Information. Query hints can be supplied. A query does not define the structure or presentation of the retrieved data. The selection identifies the metadata elements upon which the query is based. This is analogous to a projection from the source. a list of member expressions. the list is interpreted as a tuple of members. {required} When optional, this filter will be applied only if all the parameters referenced by the filter expression have been provided with values. If the filter expression does not refer to any parameters, then this filter will always be applied. When prohibited, this filter will never be applied, which is useful for testing and authoring purposes. Default: "required". {false} Specifies that when "false", this condition will be applied to detail database rows from the tabular result set prior to aggregation and summarization. Any reference to a fact (aggregate) item in this expression will be interpreted as the individual database value before it has been summarized. When "true", this condition will be applied to the summarized rows; that is, after one or more detail rows have been aggregated into one summary row. Any reference to a fact (aggregate) item in this expression will be interpreted as the aggregate value of the summarized row(s). This attribute has no effect upon references to non-aggregate items, nor is it effective when automatic summarization is disabled (see "autoSummary" attribute of the selection element). This attribute has no effect in all cases for OLAP data sources. {required} When optional, this filter will be applied only if all the parameters referenced by the filter expression have been provided with values. If the filter expression does not refer to any parameters, then this filter will always be applied. When prohibited, this filter will never be applied, which is useful for testing and authoring purposes. Default: "required".