The "Demo Database" option is best if you want to get a feel for how the program works. Recommended for use during the trial period.

The "Empty Database" option is best if you are starting from scratch. If you aleady have the Demo database installed, you will need to manually delete it before using the installer again (the default location the the database files is C:\Users\Public\Documents\AIT\TO3000, Version 3D\db. Delete the entire folder if you need to start from scratch).

Do not install a database if you already have one from the current version (although the installer will never tamper with an existing database anyway, regardless of the option chosen).