That's like the US model that has been in place for decades, if not longer.
Pretty simple really.
The condition book is the schedule of races for a given track during a certain period of time, usually a few weeks or a month. It is this schedule that provides a framework for trainers to develop the training regimens for their horses for this time period. While this seems straightforward, there are a number of factors that can change the timing of races. You see, just because a race is in the condition book doesn’t mean that enough horses will enter the race to warrant it being used. That is why you’ll see substitute races in the book as well. These are races that also get entries and can be used in place of another race on the card. Fortunately, stakes schedules are typically published weeks or months ahead of time, so with certain horses planning ahead is much easier.