The Washington system paired overall national allowances with a normal 27,000-ton unit ceiling and an exception for two larger converted carriers. Lexington and Saratoga used that exception to combine 33,000-ton standard displacement with high speed, large air groups, and eight-inch guns. The London definition distinguished purpose-built carriers from battleships, cruisers, or destroyers that merely carried flying-off platforms. Rules for ships of 10,000 tons or less and for guns above 6.1 inches narrowed opportunities to evade the carrier category. Naval architecture responded directly to these legal definitions.
Chapter · 30:46-37:59
Carrier treaties closed tonnage and armament loopholes
Treaty clauses capped carrier displacement and guns, enabled two 33,000-ton conversions, and then tightened rules for small carriers and aviation decks on other warships.