This program is a cheat program. It will enable you to do things that are not possible in the standard Transport Tycoon Deluxe.
If you think your enjoyment of the game might be reduced by using cheats, you should not use this program. Personally, I like TTD much more with some of the more annoying things removed, and the missing things added.
Any use of the sign cheat will mark your savegame permanently. If you intend to participate in a competition, you should not use them (unless they are permitted), as this can easily be found out. The rest is more or less obvious to find out anyway.