Defines the moment the script is injected. In opposition to other script handlers, @run-at defines the first possible moment a script wants to run. This means it may happen, that a script that uses the @require tag may be executed after the document is already loaded, cause fetching the required script took that long. Anyhow, all DOMNodeInserted and DOMContentLoaded events that happended after the given injection moment are cached and delivered to the script when it is injected.