High Quality Content by WIKIPEDIA articles! AS4 is a Conformance Profile of the OASIS ebMS 3.0 specification, and represents an open standard for the secure and payload-agnostic exchange of Business-to-business documents using Web services. Secure document exchange is governed by aspects of WS-Security, including XML Encryption and XML Digital Signatures. Payload agnosticism refers to the document type (e.g. purchase order, invoice, etc) not being tied to any defined SOAP action or operation.