Stupid Question...What is the Code All About?

Is it something that came only with the Limited Edition, or does everyone get it? What is it exactly? Sorry, don’t keep up with this kind of thing that closely.

343 has been sending emails out with a code that unlocks the last 6 Specializations that were not available during release (unless you had the Limited Edition).

If you’ve played by November 20th and played 100 matches, you will receive the code.