Historical Rules · 15 February 2021
Rule 611.3b
Official source text from the 15 February 2021 Rules release
The effect applies at all times that the permanent generating it is on the battlefield or the object generating it is in the appropriate zone. Example: A permanent with the static ability “All white creatures get +1/+1” generates an effect that continuously gives +1/+1 to each white creature on the battlefield. If a creature becomes white, it gets this bonus; a creature that stops being white loses it.