SOAP header for authentication etc

SOAP specification does not explicityly define the structure of
<SOAP-ENV:Header> element. It leaves
applications to include whatever they want within <SOAP-ENV:Header>.
Typical header entries, mentioned in the
specification. include authentication, transaction management, and
payment etc.

Are there any standard or convetion for specifying authentication etc
within <SOAP-ENV:Header>?

Andy Feng