Has anyone experimented with secret annotations in prompts?

In older SD models, we could include things like \[some message::0\] in prompts — text that would be ignored by the model but still included in the raw input. This allowed us to embed metadata or trigger filters without affecting the image generation.

For example, we used \[ContentLabel::0\] to signal age restrictions. Our filter system treats this as a PG-13 banned prompt keyword, so users could self-label their content by adding it.

However, it seems that in newer models, this trick no longer works. Possibly because prompt weighting syntax like :: is no longer interpreted the same way — or ignored entirely.

Did anyone find a working alternative? It’s important for us since we rely on this system to label and filter user submissions.