The second major use for temp-tables is to let you pass a set of data from one routine to another as a parameter. A routine is a generic term that includes external procedures, internal procedures, and user-defined-functions.
In particular, passing a temp-tables as a parameters is useful when you need to pass a set of one or more records from one OpenEdge session to another. This book does not cover the sending of data between an AppServer session and a client session, but the next test procedure simulates this by building a temp-table in a procedure that has no user interface, and then passing the temp-table to a separate procedure that manages the UI. The UI procedure is the same Customers and Orders window you have been using. You'll add a second browse to it to display Order Lines for the currently selected Order.