# Projects: Further Description

The project file is new in version 5.0. For users of version 4.0 or earlier, it represents a significant shift in the way a modeling run is organized. The project file is a binary file that tracks (but does not embed) the resources used in a modeling sequence. In this documentation, these resources are generally and generically referred to as “items,” and they include all file types familiar to users of previous versions: data (.dat) files, save (.sav) files, FISH (.fis), and driver (.dvr) files. There is always a project open while the program is operating, either a newly created project requested by the user, a previously saved project that has been opened by the user, or a “temp” project that the program has created absent instruction from the user to do one of the preceding two options.

The program automatically makes the location of the project file the current working directory. This makes saving items easier and keeps project items together without having to use explicit paths or issue instructions to set a current folder. Dialogs that tap into the file system (Save…, Open…, etc.) will present the folder containing the project file as the default location when they are used.

The items that compose the active project and their current state (saved, unsaved, opened, closed, or missing) are listed in the Project pane. Users who wish to familiarize themselves with projects and how they work will be best assisted by paying attention to the state of the Project pane, since it provides a graphical representation of the project itself.

The project tracks all items used in a modeling. Items come into the project in three ways: (1) they may be loaded in manually by the user (for instance, opening a data file using the file menu); (2) they may be created directly in PFC (for instance, creating a new data file, or saving a model state at the console command line); or (3) they may be created/added during command processing (for instance, when a model save command is issued in a data file, or when the data file currently being processed program calls another data file).

Similarly, items may be deleted from the project using the Project pane. Users should keep in mind the distinction between closing a project item (which merely removes it from the PFC interface) and removing or deleting it (which not only excises it from the project, but also causes the file associated with the item to be deleted).

Finally, experienced users will have noted by now that all project items tracked in the project are themselves files that are distinct from a project file. Since the location of these files is part of what the projects monitors, working with these files (moving or renaming them, specifically) outside of PFC is liable to introduce errors or broken links within the project.