It's just the extra tracks put at the end of the official playlist of mostly more popular songs if you want to "hear more about it" from the year.
We've had it for a few years now, and I took the time in 1982 to put a distinct marker that everyone could remember so once they heard that song from Pete Townshend on the Playlist, they'd know they were entering the "Coda".
I'll suggest "Hold Me Now" from Thompson Twins released in February 1984 in the US as that distinctive track that everyone knows to mark that.
(post-edit: or add that after the Christmas songs as OB1 just noted ;-)
You say I′m a dreamer
We're two of a kind