Originally Posted by KiwiJochen

The BMW Nav OS disc contains the current version software for Mk1, Mk2, Mkl3, Mk4, NAVI01, NAVI02 and NAVI03 nav systems.

When a new release of the OS disc is released, it will contain a newer version of at least 1 (or more) nav OS software.
Normally, only the software that is under current production is updated.
All other versions have generally stopped development and remain unchanged.

Thus, on the last release (V32), NAVI03 was updated, and all other software was not changed.

Likewise, Mk3 software has remained unchanged at 3-1/63 since V22 which was released around August 2003.

> The MkIII unit that I removed from my 2002 E53 was running V22 (3-1/63) ...

You cannot state this. If you want to say this, you have to say "my nav was running V22, V23, V24, V25, V26, V27, V28, V29, V30, V31 & V32" - because all of these OS discs contain the same 3-1/63 software for your Mk3 nav.


> I am aware that I'll have to burn 2 different versions of V32 to use in my Mk III (CD) and Mk IV (DVD) units if I proceed.

No. Just make an Mode2/Form1 disc and it will update both units to the current software version held on the OS disc - provided of course that the version is different (higher or lower) to what is currently loaded in the nav.
V31 contains 3-1/63 and 4-1/100 (amongst others).
V32 also contains 3-1/63 and 4-1/100.
If you already have 3-1/63 on the Mk3 and 4-1/100 on the Mk4, then trying to load V32 will result in no change, as the software has not changed.

> Secondly, having modded the pointer icon and splash screen on my Mk IV, will I have to repeat this exercise before I burn V32? or will it remember those changes from V31?

If you modified an OS disc, the changes are on that OS disc only. If you then subsequently load a new version of OS onto the nav, then the existing OS (including grpahics, pointers, splash screens) will be overwritten by the new OS.

Remember, both V31 and V32 contain 4-1/100: ie - no changes for the Mk4.