Just had a look in my old syllabus but not much clarification there, except that the Dai and Sho don't mean anything specific to the kata, didn't know that! Perhaps simply as a way of differentiating it from Goju's Ichi and Ni series? Have written what it says here: "Gekisai Dai: Conquer and occupy - major. May also mean "Storm the Fortress". Created by Miyagi in 1940 with the purpose of teaching strong and powerful movement. Gekisai Sho: Conquer and occupy - minor. There is no reason why one is called major and the other minor. Can also mean "attack and smash, demolish, destroy, pulverize". Both kata teach strength through fluidity of motion, mobility and the utilization of various techniques. Flexibility of attack and response will always be superior to rigid and inflexible strength."