I've tried web search to find answer to my question but found only articles like how to create SOAP message without header.
SOAP header : A collection of one or more header blocks targeted at each SOAP receiver. SOAP body : Contains the body of the message intended for the SOAP receiver. The interpretation and processing of SOAP body is defined by header blocks.
And:
A SOAP message is an ordinary XML document containing the following elements:
Element - Required
Header - No
Body - Yes
...
How can be a message without header if processing of body is defined in header?
The SOAP header is optional. If a header is required, it is mainly mentioned in the WSDL file, that is bound to the webservice. The WSDL defines the functions of a webservice and the types, that are bound to the functions. It depends on how a function is defined. Some definitions need an action attribute in the soap header. Others are used by directly mentioning them in the SOAP Body. To keep it short: how a SOAP message should look like is more or less strictly defined in the webservice definition (wsdl).