where does the CDDB / MCI #come from?

Does every CD have a CDDB # and a MCI #? Is this number unique to the album? What is the difference between the two?
I am putting all my CD's into a notebook type case, and I am getting rid of the jewl cases and booklets that came with the cd. But... some of the CD's don't have any information printed on them, such as album name / album title. So what I wanted to do is take a "sharpie" and write the CDDB# or MCI# right on the top of the cd.

Hi Mark,

Both CDDB and MCI IDs are unique identifiers for the audio CD.

CDDB# comes from CDDB (present FreeDB). It is calculated from number of tracks, length and position of each track. FreeDB database is organized by category and CDDB#, so when application connects to FreeDB server, it uses CDDB# to access specific album data. If OrangeCD doesn't have CDDB# on file, it cannot access FreeDB.

MCI# is the unique number assigned to CD by Windows. I don't know how it is generated - and I doubt anyone ouside Microsoft knows. It is used to reference CDs in cdplayer.ini file.

Regarding your case, why don't use reference numbers? You can type in reference # on CD Properties, Personal page. Also, you can automatically assign numbers to a range of CDs via Album/Renumber menu.

Try it out, because short reference numbers are much easier to read and remember than 8-digit hexadecimal IDs.