Soap is used for testing Webservices related to Oracle Fusion
So, we have a option to check WSDL link in Oracle official documentation as well. Let us see how to navigate...
Search for docs.oracle.com and I am choosing Financials module
Search for SOAP Web Services for Financials and click on HTML
There will be many in columns in the Request, to know which column is used for what purpose, we have Description column. For an example opening Invoice Header