PDFWAC 260-52-020
Post position.
Post position will be determined publicly by lot in the presence of the racing secretary or his/her deputy, a steward or steward designee. In the event of a scratch at a designated time, and if "also-eligible" horses are listed, all horses will move up in post position order; except in the case of a race on the straightaway, in which case the also-eligible must take the starting position of the horse scratched. The above rule will apply unless the association specifically states otherwise in its stakes or condition book.