The Header element further supports two attributes, actor and mustUnderstand. The actor attribute indicates which node in the message path should process the header blocks.

When traversing between a sender and a receiver along the message path, not all parts of a SOAP message might be intended for the final receiver or endpoint. A few parts, such as the header blocks, might be intended for one or more nodes between the endpoints. These nodes could be applications that either receive or process the message and forward it further.

If the actor attribute is not present, it implies that the message is intended for the final recipient. In the syntax for the actor attribute, the namespaceURI indicates the endpoint.

In the code example, the actor attribute is used in the Header element and the path name indicates the namespaceURI of the endpoint.