Not all SOAP headers require processing by the recipient. However, if a SOAP header is marked with the MustUnderstand attribute equal to "true", processing is required. Failure to process the header when it resides within a SOAP 1.2 request generates a System.Web.Services.Protocols.SoapHeaderException with the SoapException.Code property set to Soap12FaultCodes.MustUnderstandFaultCode. If the SOAP request resided within a SOAP 1.1 request, the SoapException.Code property is set to SoapException.MustUnderstandFaultCode.

Both SOAP 1.1 and 1.2 define MustUnderstand SOAP fault codes differing only by the version of the SOAP protocol used to send the SOAP message. This field represents the SOAP 1.2 version, and the SOAP 1.1 version is represented by SoapException.MustUnderstandFaultCode. The two fields map to different qualified names, but you can check whether the SoapException.Code property is either one of the fault codes by calling the SoapException.IsMustUnderstandFaultCode(System.Xml.XmlQualifiedName) method.

Namespace: System.Web.Services.Protocols
Assembly: System.Web.Services (in System.Web.Services.dll)
Assembly Versions: 2.0.0.0
Since: .NET 2.0