Book excerpt: NIST's Manufacturing Engineering Laboratory (MEL) is developing standards that promote interoperability among members of the U.S. automotive supply chain. This study assesses the costs of imperfect interoperability to the U.S. automotive supply chain and describes the sources of these costs. This study estimates that imperfect interoperability imposes at least $1 billion per year on the members of the U.S. automotive supply chain. By far, the greatest component of these costs is the resources devoted to repairing or reentering data files that are not usable for downstream applications.