Ah. In my original post, I meant to ask if there was a `document.is_article` (not `document.is_zone`) value.

With this implementation, if we ever add a fourth page type (something other than normal articles, template pages, and zones) that page will also get the *Convert to Zone* link. Do we only want this link for normal articles? If so, I think we should change this to `and document.is_article` lest we open the door for a future bug.