The U.S. company OpenAI began a limited preview of its next-generation “GPT-5.6” model series on June 26 (local time). It consists of three models: the flagship “Sol,” “Terra” for everyday business tasks, and the fast, inexpensive “Luna.” The names are said to represent a “hierarchy of capabilities” (OpenAI has not explained the origins of the names, but Sol, Terra, and Luna are Latin words referring to the sun, Earth, and moon, respectively). The models a