# 1.9.2 Install Directory

- `xtrkcad.xtq` is the main parameter file which contains definitions for each scale. It also includes turnout definitions for the demos and lists the playback (.xtr) files for the demos.

- `params` directory contains `*.xtp` files which are the XTrackCAD Library parameter files. These files (`atlasn.xtp, pecon55.xtp, ...`) contain definitions for turnouts, sectional track pieces and structures. These files to be used are selected in the Parameter Files (Section 2.5.5) dialog.

- `xtrkcad.chm` (on MS-Windows) is the XTrackCAD help file.

- `xtrkcad.exe` (MS-Windows) or `xtrkcad` (Linux) is the XTrackCAD program.

- `xtrkcad.tip` contains the Tip of the Day information accessible from the Help menu or shown during startup.

- `xtrkcad0.ini` specifies the location of the XTrackCAD working directory (MS-Windows only).

- `demos` directory contains `*.xtr` which are the XTrackCAD demonstration files which can be run via the Help>Demos menu item.

- `examples` directory contain some example `.xtc` files