Promise theory as a way to design systems for team interaction. Promise theory—devised by technologist and researcher Mark Burgess—explains how and why it is preferable to construct inter-team relationships in terms of promises rather than in terms of commands and enforceable contracts. For example, by adhering to the meaning of the major/minor/patch/build numbering indicated by semantic versioning (SemVer), the team promises not to break software that depends on their code.6