Need help interpreting this rails asset file extension: foobar.js.jst.jsthtml.haml

I've inherited a Ruby on Rails & AngularJS web app. Some of the static assets have the file extension.js.jst.jsthtml.haml, and I'm trying to unpack what each part of the extension means:

• .haml is the rails HAML template processor
• .jsthtml is ???
• .jst is the rails javascript template precompiler?
• .js is used to indicate that the resulting file is a javascript template

Can someone help me flesh this out, especially what the .jsthtml extension is for?