If you want to generate new parameters, click the Check button on the Web Services (Provider) window. For more information, refer to: Checking a Web Service Method.
The sequence number (seqno) of a parameter is the order of the parameter in the Body of the SOAP message. This sequence number is important in a document-oriented message, which does not contain parameter names.
It is also important for an output parameter: the sequence number of an output parameter must reflect the order of the associated output expression in the SQL Statement of the method.
The parameter name is important for input parameters. Each input parameter used in a SQL Statement must have a corresponding input parameter name. It is also important in a Document-oriented method: the parameter name corresponds with the first element in the XML message.
Parameter names must be unique (case sensitive) within a method, and must be valid names for XML elements: they must start with a letter or underscore, and can only contain letters, digits, underscores, hyphens (-), and full stops (.). Furthermore, for a document-oriented method, there cannot be a parameter with the same name in another document-oriented method of the same web service.
Two modes of web service parameters are supported: In and Out.
XML Data type is the XML type of the parameter exchanged with the client application. It represents the name of a simpleType or complexType as defined in an XSD schema pointed by the Namespace Alias.