What does &mdash mean?
Answer: When you see "&mdash" on a Web page or in an HTML e-mail, it is really supposed to be a long dash (like this: — ). An mdash, also known as an "em dash," is a dash that is the width of the capital letter M. It is longer than an "en dash," which is the width of a capital N.
If "&mdash" appears in a Web page or e-mail, it means the HTML was not written correctly. Therefore, you are seeing part of the actual HTML instead of the dash that should be appearing. Many text symbols are displayed using HTML codes, and an mdash is just one of many. The HTML code "—" can also be used for an mdash.