CREATE TABLE table_name_84 (play_off VARCHAR2, events VARCHAR2, season VARCHAR2)

Which Play-Off has Events of , and a Season of a-6?
SELECT play_off FROM table_name_84 WHERE events = "–" AND season = "a-6"
SELECT "play_off" FROM "table_name_84" WHERE "a-6" = "season" AND "events" = "–"