Class seniority is based off of lowest last 4 of SSN. Vacancies are as needed throughout the system. It's been about half Bus and half 80 the last 6 months with a few 757 spots in there. I would imagine the MD80 and definitely the 757 vacancies are going to begin to disappear in a big way, given the transition. IWA is already going all Airbus, PIE is next in August followed by AVL in November, the 757 in Dec, and then SFB and LAS by "late 2019".