The Open Access handler is located on the system when the file is opened. For all subsequent operations until the file is closed, the same handler is called.
For example, a file is defined with keyword HANDLER(handlerName).
If variable handlerName has the value 'MYPGM' when the file is opened, and program MYPGM is found in library MYLIB, then program MYLIB/MYPGM will be called to open the file.
If variable handlerName is changed to have the value 'MYSRVPGM(myProc)' before an input operation, this will have no effect. Program MYLIB/MYPGM will be called to handle the input operation.
