The EDG REST Interface: The EDG REST interface allows users to output content from the EDG catalog using a URL. EPA specific example: https://edg.epa.gov/metadata/rest/find/document?requestParameter
The EDG Search Widget:The EDG Search Widget allows users to embed a simple search tool into a web page.
The EDG CS-W Interface:The CS-W Interface allows users to query the EDG catalog using the CS-W Specification. EPA specific example: https://edg.epa.gov/metadata/cswequest=GetCapabilities&Service=CSW&Version=2.0.2