Treaty gray areas and planned escort-carrier conversions

Hybrid and auxiliary aviation ships could sit in awkward treaty categories. Seaplane carriers occupied a gray area because treaty definitions concentrated on conventional aircraft carriers and their armament. Some ships were merely convertible, while others were planned from the start as future escort carriers. The Taiyo-class liners belonged to the latter category, with one hull converted while still on the stocks. Japan used merchant construction as a carrier reserve, although the plan still fell short of producing enough useful wartime strength.