Data standards are a powerful, real-world tool for enterprise interoperability, yet there exists no rigorous methodology for selecting among alternative standards approaches. This paper is a first step toward creating a detailed engineering basis for choosing among standards approaches. We define a specific sub-problem within a community’s data sharing challenge, and focus on it in depth. We describe the major choices (kinds of standards) applied to that task, examining tradeoffs. We present characteristics of a data sharing community that one should consider in selecting a standards approach—such as relative power, motivation level, and technical sophistication of different participants—and illustrate with real-world examples. We then show that one can state simple decision rules (based on engineering experience) that system engineers without decades of data experience can apply. We also comment on the methodology used, extracting lessons (e.g., “negative rules are simpler”) that can be used in similar analyses on other issues.