What it is
STANAG 4778 is a NATO Standardization Agreement, currently Edition 1, promulgated 26 October 2018. Like most STANAGs, it is not a technical specification in its own right. It is the agreement by which NATO nations commit to ratify and implement ADatP-4778, Edition A, the Allied Publication that defines NATO's metadata binding mechanism: a standardized way of tying metadata to information so that sharing partners can trust it in a data centric environment. The technical detail a reader usually wants sits inside ADatP-4778, not inside this six-page cover. Read on its own, STANAG 4778 requires almost nothing of a supplier directly: its obligations run to nations, and it reaches a contractor only indirectly, once a nation has implemented it and a contract or tasking brings ADatP-4778's requirements into play.
Who it binds, and how
STANAG 4778 is explicit that it binds nations, not suppliers. Its letter of promulgation describes the enclosed agreement as one "which has been ratified by member nations, as reflected in the NATO Standardization Documentation Database (NSDD), is promulgated herewith." Ratification and implementation are separate steps, and once ratified, the agreement is "effective upon receipt and ready to be used by the implementing nations and NATO bodies." So "is STANAG 4778 mandatory" has no single answer: it depends on whether a given nation has ratified and implemented it, and, for a supplier, on whether a specific contract or tasking then invokes ADatP-4778.
Why the agreement exists
The document states the interoperability requirement plainly: "There is a requirement to bind metadata to information to enable trust between sharing partners in a data centric environment." It adds: "A standardized approach to binding metadata is necessary for common interpretation of binding." That is the whole of what STANAG 4778 itself says about the problem; ADatP-4778 is where the standardized approach is actually defined.
From ratification to operational use
Ratifying the STANAG is not the same as putting it into practice. The document is precise: the agreement "is implemented when a nation has issued instructions that all national documents will follow the provisions of this agreement." That is a national, internal step, separate from and later than ratification. Nations are invited to report their effective implementation, and partner nations their adoption, both in accordance with AAP-03.
What it does not cover
STANAG 4778 names no detail of the metadata binding mechanism itself - no data model, no schema, no binding format - all of that is in ADatP-4778. It also states plainly: "This STANAG does not supersede any document." There is no earlier edition replaced by this one. The document names no other related documents, and no assessment or certification scheme of its own: the only stated check on the agreement is procedural, described below.
Review and governance
The STANAG "is to be reviewed at least once every five years," with the result recorded in the NSDD, and any nation or NATO body may propose a change at any time through a standardization proposal to the tasking authority. It is supervised under the authority of NATO's DPC, DPC, CaP1, DC2S CaT.