I didn't know, the order of of the procedures under implementation is important.
Pascal is strictly declare before use. So if you call a function before it is declared (either a declaration
in the interface, or code in the implementation section), you need to declare the procedure header only forward.
This is usually not done as a matter of routine. I only have an handful of forwards in my framework which are hundreds
of units. (though admitted, in OOP code you declare more, so it is less needed)
In case needed look up "forward" in the manual.