What it is
An agreement, not the doctrine itself
STANAG 6538 is a short agreement, not the doctrine it exists for. That doctrine is AJP-3.23, Allied joint doctrine for countering weapons of mass destruction in military operations, edition A, and everything substantive is in the publication rather than the cover. The agreement's own purpose is to provide guidance to military authorities and inform NATO political and civil authorities of their recommended roles in countering weapons of mass destruction efforts within a joint and multinational framework.
That distinction is the thing readers most often have wrong about a STANAG. It is the instrument by which NATO nations commit to implement a standard. A nation ratifies it, implements it domestically, and a company meets it only because a contract or a tender says so. Ratification and implementation are separate steps, a nation can ratify with reservations, and so "is STANAG 6538 mandatory" has no general answer, only a contractual one.
How a nation implements it
The agreement is "effective upon receipt for use by the participating nations and NATO bodies", and nations are invited to examine their ratification and tell the NATO Standardization Office what they intend. Responses are recorded in NATO's Standardization Document Database.
This STANAG and AJP-3.23 are implemented once the procedures set out in AJP-3.23 have been written into national regulations, manuals and training. Allies and NATO bodies report their implementation details through the electronic reporting tool (e-Reporting), and partner nations are invited to do the same.
What it does not do
It describes no certification, no notified body, no government quality assurance and no audit of any organisation. The only check it names is of itself: a review in line with AAP-03, with the result recorded in the NSDD. And it places no obligation on a supplier: nothing in the text addresses a manufacturer, a contractor or a product.
Edition and the doctrine family
This is Edition 1, promulgated 20 September 2023. "This STANAG does not supersede any document." It covers AJP-3.23, Edition A, and lists seven other STANAGs as related, each one the cover for an Allied joint doctrine publication in the same family: STANAG 2437 (AJP-01), STANAG 2490 (AJP-3, the conduct of operations), STANAG 2451 (AJP-3.8, comprehensive chemical, biological, radiological and nuclear defence), STANAG 2528 (AJP-3.14, force protection), STANAG 2616 (AJP-3.22, stability policing), STANAG 2526 (AJP-5, the planning of operations), and STANAG 2596 (AJMedP-7, CBRN medical support doctrine).