Substitute races may be provided for the program of each day and shall be so designated. Declarations in races not filling shall be posted. A substitute race or a race divided into two divisions shall be used only if regularly scheduled races fail to fill. If a regular race fills it shall be raced on the day it was offered. Overnight events and substitutes shall not be carried to the next racing day.
58 Pa. Code § 183.139
This section cited in 58 Pa. Code § 181.1 (relating to definitions).