Can you have more than 40 cards in your main deck at organized play events like Nexus Nights?

Ruling: At organized play level (OPL) events including Nexus Nights, your main deck must be exactly 40 cards. More than 40 cards is only allowed for casual kitchen table play.

Nuances:

• Sideboards must be exactly 0 or 8 cards, nothing in between
• This exact deck size requirement applies to all constructed events (Nexus Nights, Summoner's Skirmish, Regional Qualifiers, Regional Championships, etc.)