- File Interfaces:
  - Java supports the use of Interfaces.
    - An interface is a definition of the methods that will be present in any implementing class.
    - A class can implement more than one interface if it so chooses, it just needs to provide all of the methods required by all of the implemented interfaces.
    - An interface can be thought of as a guaranteed contract stating that "by implementing this interface I guarantee this class will implement these methods specified by the interface."
    - This allows the interface to be used as a reference type that allows any class implementing the interface to be used without altering the code.
  - NeXtMidas makes use of interfaces for plotting and listing files.
    - Any file whose handler implements `PlotFile` can be plotted by `PLOT`.
    - Any file whose handler implements `ListFile` can be listed by `LIST2`.

X-Midas Users Take Note:
File support for X-Midas is part of the system libraries and can not be modified without altering the X-Midas baseline. In NeXtMidas option trees can add their own file handlers, at run-time, without altering the NeXtMidas baseline.