If a named map is too restrictive, consider adding an overlay in your mapping request. An overlay is a way of customizing a named map that cannot be customized directly.
Overlays can be layers or themes, and can be based on tables, inline tables and views. For example, an overlay of a feature layer can include features from an in-memory table as the result of a search query.
Overlays are part of the mapping request. They are not stored in the repository. In a SOAP request the overlay is defined in an OverlayList. In a REST request, the overlay is defined in the JSON object.
For a SOAP example, go to the Spectrum Spatial SOAP Mapping Service Demo Page at
http://<server>:<port>/Spatial/MappingService/DemoPage.html and choose
Render Named Map with BarLayer Overlay from the drop-down list.
For a REST example, see Map with Pie Layer Overlay.