Like FM2436, I no longer have access to the changes made leading up to BK1 & 2. However, the last contract negotiated normally became effective in 1998 and everything since have been amendments to that contract. Under the scope provision of that contract the limit on the number of seats is 69 and there are limits on the number on "turbine engine without an external propellar" (non-turboprop) aircraft.
As I recall, like fr8tmastr, all the scope changes since that contract have addressed the number and seating capacity of "small jets", or non-turboprops. If that's correct, the turboprop limit remains 69 seats.
Jim