The topic Service Parameters allows you to return the results of a Service Definition Set as the value of the custom operator.  This can be useful if you need to use service directly in a calculation or return it for fulfillment purposes.  The multi-choice field allows you to either specify <Base Service Set>, to reference the Service Definition Set specified in the Member Data section of the Census Specifications, or to select any Service Definition Set from those that have already been defined in the library. The button allows you to access the Service Definition Set library to create new definitions or modify existing ones.

Contrary to the operation of most custom operators (that the default custom operator parameterization produce the same result as the standard operator), the standard #SERVICE operator is not based on a Service Definition Set.  Rather, it returns a duration (or elapsed time) relative to the database field component provided as its right argument.