I wasn't looking for a wikipedia link, i'm quite capable in finding those myself. ;)
This was more of a meta-mini-rant about how we have these tools available to efficiently communicate meta-information along without main message, but especially news media outright refuses to make use of it.
In context (an article in a design/advertising magazine) I think it would just be taken as a common term the audience would be assumed to know. Same way that a magazine aimed at programmers wouldn't typically define "functional programming" or "garbage collector".
This is not trying to pass meta-information, but to sell to a prospect. The last thing you want them to do is go to another site rather than clicking on your call-to-action.
This was more of a meta-mini-rant about how we have these tools available to efficiently communicate meta-information along without main message, but especially news media outright refuses to make use of it.