Time Difference In Query

Does anyone have the syntax on how to perform a time difference in a Sage Query?

Here is an example query:

SELECT "SO_SalesOrderHistoryHeader"."SalesOrderNo", "SO_SalesOrderHistoryHeader"."CustomerNo", "SO_SalesOrderHistoryDetail"."ItemCode", "SO_SalesOrderHistoryDetail"."QuantityShipped", "SO_SalesOrderHistoryHeader"."LastInvoiceDate", "SO_SalesOrderHistoryHeader"."UDF_TIMEIN", "SO_SalesOrderHistoryHeader"."UDF_TIMEOUT"

FROM   "SO_SalesOrderHistoryHeader" "SO_SalesOrderHistoryHeader", "SO_SalesOrderHistoryDetail" "SO_SalesOrderHistoryDetail"

 

As you can see, we have a TimeIn and a TimeOut field.  Is there any way to return another column that calculates the time difference?  If so, what would the syntax of that be?

 

Thanks!