//I have simplified (truncated) the code to make it readable in this post.
//First, Sales Order Header and Detail are invoked
SO_Header_Bus = pvx.GetType().InvokeMember("NewObject", System.Reflection.BindingFlags.InvokeMethod, null, pvx, new object[] { "SO_SalesOrder_bus", oSS });
SO_Detail_Bus = SO_Header_Bus.GetType().InvokeMember("oLines", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.GetProperty, SO_Header_Bus);
//Get new order number to work with and set it
pvxGetParam(SO_Header_Bus, "GetNextSalesOrderNo", out sNextOrderNo, out sLastErrorMsg);
pvxSetParam(SO_Header_Bus, "SetKey", sNextOrderNo, out sLastErrorMsg);
//Other parts of the order are set
pvxSetString(SO_Header_Bus, "OrderType$", sOrderType, out sLastErrorMsg);
pvxSetString(SO_Header_Bus, "ARDivisionNo$", sDivNo, out sLastErrorMsg);
pvxSetString(SO_Header_Bus, "CustomerNo$", sCustNo, out sLastErrorMsg);
pvxSetString(SO_Header_Bus, "SalespersonDivisionNo$", sSPDivNo, out sLastErrorMsg);
pvxSetString(SO_Header_Bus, "SalespersonNo$", sSPNo, out sLastErrorMsg);
pvxSetString(SO_Header_Bus, "CustomerPONo$", sCustomerPONO, out sLastErrorMsg);
//!!here is the payment information stuff …
//
//THIS WOULD BE "CreditCardGUID$" NOW BUT ITS NOT IN THE SALES ORDER HEADER OR DETAILS
pvxSetString(SO_Header_Bus, "EncryptedCreditCardNo$", sCreditEncryp, out sLastErrorMsg); //"CreditCardGUID$" error ‘column not on the IO list’
pvxSetString(SO_Header_Bus, "ExpirationDateMonth$", sCreditExpMonth, out sLastErrorMsg);
pvxSetString(SO_Header_Bus, "ExpirationDateYear$", sCreditExpYear, out sLastErrorMsg);
pvxSetString(SO_Header_Bus, "TermsCode$", sPaymentTerms, out sLastErrorMsg);
pvxSetString(SO_Header_Bus, "ShipToCode$", sShipToCode, out sLastErrorMsg);
pvxSetString(SO_Header_Bus, "PaymentType$", sPaymentType, out sLastErrorMsg);
//Order detail stuff, not important…just showing a bit for context
pvxNoParam(SO_Detail_Bus, "AddLine", out sLastErrorMsg);
pvxSetString(SO_Detail_Bus, "ItemCode$", sItemCode, out sLastErrorMsg);
//Write Details
pvxNoParam(SO_Detail_Bus, "Write", out sLastErrorMsg);
//Write Header
pvxNoParam(SO_Header_Bus, "Write", out sLastErrorMsg)

==========================

As you can see from the above, EncryptedCreditCardNo used to be in the sales order header business object.  

The new field is CreditCardGUID but it is not in the SO header.  Instead, it is in the SO Payment business object.  

I should think that I must additionally invoke the new payment object but where?  and what fields must be used?  In the SQL database, the primary key fields are SalesOrderNo and PaymentSeqNo.  There must be a "getnextpaymentseqno" function?  What is it?  What credit card fields must I then set? thanks

//So I got it to work.  I can now just automate batch sales orders with various credit cards
//You must Invoke the Sales Order Header business object first, then invoke a SO detail object using the name ‘oLines’, then the new thing you have to do is use the header object again to invoke a SO payment business object using the name ‘oPaymentObj’. Some of the Header object’s variables are moved into the Payment object. Also the Payment object needs to make a new record or to be used to invoke ‘nAddPayment’ so that variables related to the credit card may be set.

//I have simplified (truncated) the code to make it readable in this post.
//First, Sales Order Header and Detail are invoked
SO_Header_Bus = pvx.GetType().InvokeMember("NewObject", System.Reflection.BindingFlags.InvokeMethod, null, pvx, new object[] { "SO_SalesOrder_bus", oSS });
SO_Detail_Bus = SO_Header_Bus.GetType().InvokeMember("oLines", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.GetProperty, SO_Header_Bus);
SO_Payment_Bus = SO_Header_Bus.GetType().InvokeMember("oPaymentObj", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.GetProperty, SO_Header_Bus);

So now the differences between MAS200 and SAGE100 (with the Exchange Vault) and my previous post are these:
if (creditCardTransaction){
pvxNoParam(SO_Payment_Bus, "AddPayment", out sLastErrorMsg);
pvxSetString(SO_Payment_Bus, "CreditCardGUID$", sCreditEncryp, out sLastErrorMsg);
pvxSetString(SO_Payment_Bus, "ExpirationDateMonth$", sCreditExpMonth, out sLastErrorMsg);
pvxSetString(SO_Payment_Bus, "ExpirationDateYear$", sCreditExpYear, out sLastErrorMsg);}
pvxSetString(SO_Header_Bus, "TermsCode$", sPaymentTerms, out sLastErrorMsg);
pvxSetString(SO_Header_Bus, "ShipToCode$", sShipToCode, out sLastErrorMsg);
pvxSetString(SO_Payment_Bus, "PaymentType$", sPaymentType, out sLastErrorMsg);
//…and so on

//and finally, Here is how I invoked the objects
pvx = System.Activator.CreateInstance(Type.GetTypeFromProgID("ProvideX.Script", true));
pvx.GetType().InvokeMember("Init", System.Reflection.BindingFlags.InvokeMethod, null, pvx, new object[] { MAS90Path });
oSS = pvx.GetType().InvokeMember("NewObject", System.Reflection.BindingFlags.InvokeMethod, null, pvx, new object[] { "SY_Session" });
//pvx and oSS are just base System.Object objects
//just FYI: public object InvokeMember(string name, BindingFlags invokeAttr, Binder binder, object target, object[] args);
//So the secret sauce is that “string name” which is why I had been asking all these months for help / documentation but I never got any, I just brute force guessed.