Rules glossary
↑ Parent rule: 508.3 Triggered abilities that trigger on attackers being declared…
508.3a An ability that reads “Whenever [a creature] attacks, . . .” triggers if that creature is declared as an attacker. Similarly, “Whenever [a creature] attacks [a player, planeswalker, or battle], . . .” triggers if that creature is declared as an attacker attacking that player or permanent. Such abilities won’t trigger if a creature is put onto the battlefield attacking.
No sub-rules.