I'm looking at biting the bullet and upgrading my MKIII to a MKIV, most likely bought off Ebay. Reading through this the SIB says:

NAVIGATION COMPUTER REPLACEMENT - MK III AND DVD NAV
When replacing a defective MK III or DVD NAV computer, a configuration signal is required to allow the new computer to load the correct software for its respective application. This is generated by using the SSS (Software Service Station) loaded with the latest Progman version, and the navigation system operating software CD V17.1 or V32.

1. Connect the Deutronic battery charger to the vehicle.
2. Connect the SSS via a diagnostic head or an O(P)PS (for D-CAN vehicles) to the vehicle.
3. Open a "New session" in Progman; select "Load SW" and follow the on-screen messages.
4. Select "Retrofits".
5. Select "Languages".
6. First select "Display" to select and/or check the correct languages.
7. Then select "Navigation" to select the languages for the NAV system.
8. At the prompt "Is the CD-ROM present?" select "Yes", but do not insert the navigation CD into the Nav Computer yet!
9. First select the main language and then an additional language (the choices are English, French, Italian, Spanish, and German).
10. NOTE: The gender of the announcer's voice (male or female) can no longer be selected.
    • MK I, MK II & MK III: Only male.
    • DVD-Top NAV, NAVI01, NAVI02 and NAVI03: Only female.
11. After activation of the automatic coding, the DIS tester tells you to follow the instructions on the monitor for navigation CD installation.
12. Place the navigation CD into the navigation computer CD drive.

I thought having read a few retrofit guides that it was simply plug and play between the two, but the above seems to suggest that the MKIV needs to be coded to the car. So my question is do I need to get it coded, or is the above in reference to a brand new unit without software loaded?