The Specification Domain, like its predecessors TMG and TMWG, develops specifications that set out the rules for how to design UN/CEFACT standards (Technical Specifications) and how these standards should be developed (Methodologies). When appropriate, the specifications are published also as ISO standards, e.g. the UN/EDIFACT syntax (ISO 9735) and the Core Components Technical Specifications (ISO 15000-5).

Although the primary target audience is UN/CEFACT and its standards development groups, the specifications are widely used also by other organisations for production of non-UN/CEFACT deliverables.