What are the rules for relay exchanges?

From recent NFHS rule changes and interpretations:

• Starting from the deck (Rule 8-3-4a, clarified 2025-26): one foot must be at the edge of the deck. Ancillary movement of the back foot is allowed before the start.
• Starting from a platform (Rule 8-3-4, 2025-26 interpretation): any momentum for the exchange must happen on the top surface of the starting platform. You can move from the back of the platform to the front. You can't build momentum from the deck or from any other location. Rules on the starting wedge (8-3-4c) also apply.