Historical Rules · 8 November 2024
Rule 509.4
Official source text from the 8 November 2024 Rules release
If a creature is put onto the battlefield blocking, its controller chooses which attacking creature it’s blocking as it enters the battlefield (unless the effect that put it onto the battlefield specifies what it’s blocking). A creature put onto the battlefield this way is “blocking” but, for the purposes of trigger events and effects, it never “blocked.”