Historical Rules · 1 February 2012
Rule 607.3
Official source text from the 1 February 2012 Rules release
An ability may be part of more than one pair of linked abilities. Example: Paradise Plume has the following three abilities: "As Paradise Plume enters the battlefield, choose a color," "Whenever a player casts a spell of the chosen color, you may gain 1 life," and "{T}: Add one mana of the chosen color to your mana pool." The first and second abilities are linked. The first and third abilities are linked.