Some basic aspects of Fopnu operation can be changed, at startup, by the presence of one or more .txt flag files in the same folder as the program executable.  These files don't need to have anything in them, just their presence is all that is needed.

fopnu_standalone_mode.txt
This will set the configuration file folder to the same folder that contains the program.  The lock file that is used is still placed in the default configuration file location.

fopnu_portable_mode.txt
This is intended for use from a portable media device.  The configuration file folder is set to the same folder that contains the program.  The default location for loading/saving files and the default download folder are placed in the root folder of the portable media device.  The lock file that is used is still placed in the default configuration file location.

fopnu_local_instance_check.txt
This has the same effect as fopnu_standalone_mode, except the program lock file is also placed in the program executable folder.  This has the effect of allowing multiple standalone instances on the same system, running from separate folders with separate copies of the program executable.

enable_memory_profiling.txt
This will cause Fopnu to closely track it's own memory usage, and enables charts available from the main Help menu > Diagnostics > Memory State.

enable_memory_checks.txt
This will cause Fopnu to use a special memory allocation routine that adds advanced boundary checks and several heap-checking operations.  This is experimental and should only be used for debugging purposes.