I received a question today about the Multipart-MIME examples in my Serving Word presentation. The question is, “What are all those ’3D’ letters and how can I make Word documents without them?”

The 3D is related to encodings. The most common encoding mechanism for text in a Multipart-MIME message in called Quoted-Printable encoding. In this encoding mechanism most standard symbols, numbers, and letters are left exactly as is. All other characters are encoded using an equal sign followed by the two-digit hexidecimal code for the character. For example, a tab can be encoded as “=09″ since a tab is represented by 09.

Since the equal sign is used to indicate encodings, the equal sign itself must also be encoded whenver it’s encoutered. The equal sign is represented by decimal 61 or hexidecimal 3D, and thus is shown as “=3D” in a quoted-printable encoded message.

So, whenever you encode an HTML document, which has a lot of equals signs in it, in quoted-printable format, you’re going to have a lot of “=3D” sequences in the resulting document.

Only a developer will see these, the target application which reads the quoted-printable message will convert them back to regular equal signs, so a user will never see them.

So in short, don’t worry about it, =3D is normal and user’s won’t see it.