Assuming you have a HIGH and not a PROFESSIONAL DVD, the biggest problem you are going to have is to reduce the content of the DVD sufficiently so that it fits on a 650MB CD. If the map database itself is larger than this, then you have no chance.

Navigation system it gave Not Correct CD.
I think there maybe a small file or command make it compatible only with MKIV. or maybe it is simpler.

Any ideas.

Yes, the only issue is the size.

Sorry as reply was not complete

The DVD size is only 50MB.

I managed to burin it on a CD in order to use it on MKIII but it gave the following message:
Not Correct CD in Navigation
Is the database fine same for MKIII & MKIV system.
I think there maybe a small file or command make it compatible only with MKIV. or maybe it is simpler.

Your advise highly appreciated

Hmmm... database varies greatly.
The Mk3 and the Mk4 can read the carindb file. I don't know what DVD you have, I assumed your DVD has the carindb map database file.
The Mk3 cannot read some of the newer map database formats used in the Mk4
The Mk3 cannot read the external POIs in the TPD directory
The CD TOC has to be labelled correctly for the CD to be recognised, compare with the Mk3 map CD

It will not work anyway. Mk2/3 software assume DB sector size is 2048 bytes, but in modern CD/DVD maps DB sector size set to 512 bytes.

Below are contents of some of files of new DVD and the 2004 DVD which i manged to have it work on MKIII it may help:
1. New DVD
DVD abstract

This medium contains a digital road map database for the CARiN- and VDODayton navigation compatible systems.
The medium can be used in `product' target-systems, for the "CARiN on PC" application, and for CARSiM.

Tool :4.0.03
Date :2007-04-10
Operator :uida1203
CD number :18898
Medium :Master DVD5
Navigation databases:
..._prod/NavTech/me/ag_nt_bmw_06Q4_20070330pz9.cpr
Type :non C-IQ
Event Texts :carinet16s512.20041130
TPD Database :Not available
IBA Database :Not available
CARINSYS File :Not available


security
MKA; 387922833; 119013889


Biblioger

CD-ID 18898 DB-REL 34 BSW-REL 10 11

2. 2004 DVD
This medium contains a digital road map database for the CARiN- and VDODayton navigation compatible systems.
The medium can be used in `product' target-systems, for the "CARiN on PC" application, and for CARSiM.


Tool : 3.0.5
Date : 2004-05-04

Operator : uida1203
CD number : EHVDVD_12143_3.0.5
Medium : Master DVD

Navigation database : .../NavTech/me/ag_nt_bmw_04II_20040505h.cpr
Type : non C-IQ
Event Texts : carinet16s2048.20020513
TPD Database : Not available
IBA Database : Not available
Language Loading : Not available
CARINSYS File : Not available


Biblioger

CD-ID 12143 DB-REL 29 BSW-REL 91.0 91.1 92.5 92.7 92.8 93.0 93.1 93.3 93.6 94.0 94.3 95.3 95.6 95.7 95.8 BSW-REL 96.0 96.1 96.2 97.0 98 10 11