These are not protected fields but rather text fields in a document protected for filling in forms. In Word 2007 they are the legacy form fields on the Developer Tab. If you don't see a Developer Tab see Developer Tab in Microsoft Word 2007 and 2010.

Take a look at the Add-In on Greg Maxey's page to make it simpler to use these fields. Do not mix the legacy fields with other kinds of fields unless you (1) know what you are doing and (2) really need to do so. Add Classic FormField Controls to Ribbon