A project options file (.pof) is a text file used to store project modes. Project modes currently in use in a project are stored in the workspace project file (.pjt) and updated every time you click OK to save your settings and exit the Project Settings interface.
Note that project options files are static. In other words, once you write options to a POF, those options are not automatically updated when you change the corresponding mode in the project from which the POF was created. To update the settings in a POF, you must explicitly save the changes to a file.
There are two ways to save a mode as a POF:
The mode saved in default.pof is always called Release, and it is always used to create a second default mode, called Debug, by adding the -Ga compiler flag to the existing compiler command line.