Allows you to perform complex retrievals of records from one
       or more domains or collections. You can include a FROM value
       expression in the Boolean of the RSE that forms the collection
       or record stream. The optional OTHERWISE clause lets you specify
       an alternative DEC DATATRIEVE value expression if an initial
       search of data based on an RSE produces no records. If the number
       of records in a record stream equates to zero, the alternative
       specified by the OTHERWISE clause is returned.
       Format
       value-expression FROM rse [OTHERWISE value-expression]