TADDaemon
General
TADDaemon.exe is found in the "bin" folder and comes from Trainz Asset Database Daemon. TADDaemon manages the database of all Trainz assets known to the installation. Trainz, Content Manager and other Trainz programs depend on it.
In addition to it's main task (maintaining the local database of Trainz assets), it is also responsible for asset validation, most internet communication, and other background tasks.
Technical Details
TADDaemon must be allowed through firewall because it has to connect to the internet and to communicate with other Trainz Components.
TADDaemon will shut down when Trainz is not running. If Windows prompts to 'Wait' or 'End Task' while shutting down, choose to wait for TADDaemon to finish. Avoid using 'End Task' on TADDaemon, or it will likely need a database repair on the next start. Also avoid hard powering off the machine while TADDaemon is running, for the same reasons.