What it is
What STANAG 2449 covers
STANAG 2449 is the NATO standardization agreement that gives force to ATrainP-2, Edition B, the Allied publication on training in the Law of Armed Conflict (LOAC). A STANAG is not itself a training curriculum: it is the agreement by which NATO nations commit to implement one, and the actual training content sits in the Allied Publication it covers. The interoperability requirement behind it is stated plainly: "to standardize training in the Law of Armed Conflict (LOAC) by establishing a minimum standard of training to ensure that NATO operations are conducted in accordance with LOAC, where applicable."
This is Edition 3, promulgated 26 June 2019. The cover states it "supersedes the following document: STANAG 2449, Edition/Édition 2."
Who ratifies it, and how it takes effect
A STANAG binds a nation, not a supplier or a training provider directly. Nations "are invited to examine their ratification of the STANAG and, if they have not already done so, advise the NSO of their intention regarding its implementation," and the response is recorded in the NATO Standardization Document Database (NSDD). Ratification is not the same as implementation: the agreement counts as implemented for a nation only once it has folded the STANAG's procedures into its own national orders or instructions. Partner nations are invited to adopt the STANAG separately, without the same ratification step that member nations go through.
Reporting and review
Nations are invited to report their effective implementation, and partner nations their adoption, "in accordance with AAP-03." The STANAG "is to be reviewed at least once every five years," with the result "recorded within the NSDD," and any nation or NATO body may propose a change at any time through a standardization proposal to the tasking authority.
How it's evaluated
No certification exists here, and the cover names none. What it describes is a national ratification, implementation and review cycle run through NATO's own machinery: nations report to the NATO Standardization Office, not to an external auditor or certification body. Whatever training a person or unit actually receives against ATrainP-2 is what a nation's own training authority, or a customer's contract, assesses, not something certified at the level of this agreement.