Example of a standard program

As an example we can try to read any program as a standard program. We give the packet-command


#elan156#

In typing the name (followed by <#158#>;SPMlt;RET;SPMgt;<#158#>) it is not shown on the screen. Similarly, in reading the refinements of the program only their names (not their bodies) are shown. Immediately after the reading a list of all refinements of the program is displayed on the screen, but this is not reproducible by means of the list-command because the refinements become ``invisible''. We can execute etc. the program in the usual way but we can not modify it. At most we can add new refinements.