To demonstrate that a dose-determining assay is fit for purpose, the measurement uncertainty associated with a reported release test result must be suitably small. The establishment of a corresponding product specification is inextricably linked to the tolerance for error in assigning a dose value for a vector lot. By adopting an equivalence-based lot release model which includes a total error approach to assay qualification, specific testing strategies can be evaluated quantitatively for dose error and lot release decision risks throughout the drug development process. This article aims to reinforce how the concepts tied to an equivalence-based lot release model are interrelated and applied in practice. It provides in-depth explanations of fundamental concepts and clarifies common misunderstandings for quality control, quality assurance, and regulatory affairs personnel held accountable for decisions made in vector dose assignment and product lot release.