3 rules? Well everyone knows I don't back maiden races and a race must have 8 or more runners betting for the place so I don't call them rules!

The system has only 2 rules and yesterday wasn't special, just the latest day. The TAB source is not one of the rules and is easy to work out . The second rule is more opaque than the first.

OK, the ONLY clue: 'The value is built in'