SN12 was scrapped and SN13 and SN14 were never built, to allow for SN15, the new design, to jump the queue. SN11 is next followed by SN15 and then possibly BN1

SN12 was scrapped and SN13 and SN14 were never built, to allow for SN15, the new design, to jump the queue. SN11 is next followed by SN15 and then possibly BN1, the first booster.