The Commission's Code of Practice is the recognised route to compliance on marking
The Commission has endorsed a voluntary Code of Practice on Transparency of AI-Generated Content as an adequate means of supporting compliance with the marking and detection obligations. Voluntary in name, load-bearing in practice.
A code of practice endorsed by the enforcing authority is not really optional. It is the path where compliance is presumed, and departing from it means arguing your alternative is equivalent, to the body that wrote the one you declined to follow.
That is a familiar regulatory pattern and it is generally a good one. It gives industry a concrete specification instead of a legal standard, and it lets the specification evolve without reopening legislation.
The open question is interoperability. A marking scheme is only useful if the detectors are widely deployed, and a code of practice can specify what providers embed without doing anything about who is checking. Marking without detection is a compliance artefact rather than a public protection.
European Commission — Code of Practice on Transparency of AI-generated Content → · European Commission — AI Act — regulatory framework → · Goodwin — Not delayed, not deferred: EU AI Act transparency obligations are now in force →