What is the "honor system" in Vienna?

Travel Info
I hear it is related to public transportation. Can someone please explain it further?

Travel Tips

The honor system:
If you have a ticket which is not specifically dated when you buy it, you must validate it when you get on the public transport of your choice. If you have a dated ticket (weekly, monthly etc.) you must have your pass with you at all times. Perhaps the distinction between a ticket and a pass could be used. Tickets need to be validated (stamped) in the little machine near each door. Passes don't. You just must have them on your person. You may never be asked by anyone to show you ticket or pass. However, when you least expect it an inspector may show up, present a badge and demand to see you ticket. If you don't have it you will be taken off the public transport and made to pay a very expensive fine of 500 schillings.

SPECIAL CAUTION ON THE NIGHT BUSSES. You need a special extra ticket for a night bus in addition to your regular ticket or pass. More people are fined for violating the honor system on the night busses than on any day transport.

BTW - I have traveled extensively for business all over Europe and Asia. Vienna is my #1 favorite place to go. I love Austria, it is a beautiful country, and the people are very gracious. Vienna is cool, but don't miss out on Saltzburg. There are English speaking bus tours that are phenomenal. In fact, from Vienna, we also did a tour to Prague, Czech Republic. TREMENDOUS!