I have a prospective scenario. The solution is about to create a new operation and pass the selected sales transaction line in shopping cart as parameter to the new operation.
Example behavior: 
Reference to the "View available discounts" operation. The process is, to choose an item in cart and click the operation button, The command "GetAvailablePromotionsServiceRequest" has "SalesTransaction" object as parameter. I would like to do the same behavior.
SalesTransaction salesTransaction = new SalesTransaction();
 salesTransaction.CartType = CartType.Shopping;
 salesTransaction.SalesLines.Add(ConstructSalesLine("888842543067"));
 CalculatePricesServiceRequest request = new CalculatePricesServiceRequest(salesTransaction);
 GetPriceServiceResponse response = runtime.Execute<GetPriceServiceResponse>(request, new RequestContext(runtime));
 
 GetAvailablePromotionsServiceRequest getAvailablePromotionsServiceRequest = new GetAvailablePromotionsServiceRequest(salesTransaction);
 GetAvailablePromotionsServiceResponse getAvailablePromotionsServiceResponse = 
 requestContext.Execute<GetAvailablePromotionsServiceResponse>(getAvailablePromotionsServiceRequest);
Questions: - 
1. Is there any examples in RetailSDK\Document to pass the selected sales cart as parameter to CRT?
2. If no example, please kindly guide the command in Cloud POS and CRT.