SimpleObjectAccessProtocol (SOAP) mixed with binary "opaque" attachments is SoapStone. Or Soap with embedded sand/stone in it. A reality in life.
Various mechanisms exist to cater to the need to pass digital signatures, media objects, etc between applications using SoapProtocol. See http://msdn.microsoft.com/webservices/understanding/advancedwebservices/default.aspx?pull=/library/en-us/dnwebsrv/html/opaquedata.asp
DimeInSoap? is an example of SoapStone. It is said to be supported in SoapToolkit v3 and the more commonly used SwA (Soap with Attachments) is not supported.
Has to be careful with the brand of Soap one uses, I suppose.