Vertical IS standards prescribe data structures and definitions, document formats, and business processes for particular industries, in contrast to horizontal IT standards, which concern IT characteristics applicable to many industries. This paper explores the potential effects of vertical IS standards in the US home mortgage industry by examining technical implementation requirements. This paper makes two important contributions. First, as one of the first in-depth cases of the benefits of e-business standards in a particular industry, this paper can serve as a foundation for future theoretical development. Second, although other authors have noted that the initiators' benefits from adopting interorganizational standards like EDI dependent on how their partners implement the standards, we describe in depth the technical choices that lead to partners' suboptimal implementations and the business considerations that lead them to make those choices.