nervgh/angular-file-upload — pull request #80 by chrkhl (2014-03-05 20:27:39+00:00)
Title: Naming Conventions: Don't use $ or ng prefix for your own services/directives

"Best Practice: In order to avoid collisions with some future standard, it's best to prefix your own directive names. For instance, if you created a directive, it would be problematic if HTML7 introduced the same element. A two or three letter prefix (e.g. btfCarousel) works well. Similarly, do not prefix your own directives with ng or they might conflict with directives included in a future version of Angular."
(http://docs.angularjs.org/guide/directive)