The image service resource supports the following operations:
Export Image: Returns a seamless mosaicked image for the specified area.
Identify (added at 10): Identifies the content of an image service.
Query (added at 10): Query the image service.
Download (added at 10): Downloads raw raster files.
Since : ArcGIS API for Flex 2.0
Performs an identify operation on an image service resource. It identifies the content of an image service for a given location and a given mosaic rule. The location can be a point or a polygon. The identify operation is supported by all kinds of image services (Mosaic Datasets, Raster Datasets or an Image Service definition).
... For image services, the map service itself is the 'single' layer...