For the field of type file it allows you to restrict the acceptable file types (any, html, image) but dataforms does not enforce this restriction when someone enters the form. I have a file field set up where "Accepted file types" is set to "Image files." I am still able to upload PDF files. I am using Moodle 3.0.4+ (Build: 20160609) and Dataform 3.0.4 (Build: 2015111604).
How do you restrict the types of files that users can upload?