Delta has joined Sabre's Beyond NDC distribution testing and development initiative. The cross-industry group aims to speed up development and integration of New Distribution Capability technology. United and American are among previously announced airlines working with Beyond NDC. Delta also has been working with Sabre in development of ATPCO's Next Generation Storefront standards, which sorts flight options into a six-star system of tiers based on product, ancillaries and restrictions rather than traditional class tiers as defined by airlines, according to Sabre.