Historical Rules · 10 August 2018
Rule 702.42a
Official source text from the 10 August 2018 Rules release
Modular represents both a static ability and a triggered ability. “Modular N” means “This permanent enters the battlefield with N +1/+1 counters on it” and “When this permanent is put into a graveyard from the battlefield, you may put a +1/+1 counter on target artifact creature for each +1/+1 counter on this permanent.”