Maybe I'm being picky, but this seems counterintuitive. The Frotz interpreter is featured as the primary subject of the article, while the spell it was named for is mentioned parenthetically at the bottom. Would it make more sense to move the blurb about the Frotz spell to the top (and then continue with "Frotz is also a Z-machine implementation...")? 

 If someone could scratch up enough information about the Frotz spell, this could even become a disambiguation page leading to separate articles. -