According to BMW (USA - North America Discs only)

For E53 X5 (I-BUS and NAVI02/NAVI03)
DVD High 2002.1 S0001-0070-210
DVD High 2003.2 S0001-0070-309
DVD High 2004.2 99 00 0 309 800
DVD High 2005.2 65 90 0 398 542
DVD High 2006.2 65 90 0 404 346
DVD High 2007.1 65 90 0 415 621
DVD High 2007.2 65 90 0 426 554
DVD High 2008.1 65 90 0 431 723
DVD High 2009.1 65 90 2 147 669
DVD High 2010 65 90 2 158 157 - TeleAtlas

For E70 X5 & E71 X6 (DVD-CCC (Car Communication Computer)/ MOST BUS)
DVD Professional 2004.2 99 00 0 390 203
DVD Professional 2005.2 65 90 0 398 540
DVD Professional 2006.2 65 90 0 404 347
DVD Professional 2007.1 65 90 0 415 622
DVD Professional 2007.2 65 90 0 426 555
DVD Professional 2008.1 65 90 0 431 724
DVD Professional 2009.1 65 90 2 147 677 (DVD-CCC)
DVD Professional 2009.1 65 90 2 165 623 (DVD5-CCC)
DVD Professional 2010 65 90 2 158 158 - TeleAtlas


For E70 X5 & E71 X6 (CIC (Car Information Computer)/ HU (Head Unit) DVD) from October 2009
CIC - High Road Map North America Premium 2009-1 65 90 2 149 427 (2 DVD set - 15GB)
CIC - High Road Map North America Premium 2009-2 01 99 0 037 287 (3 DVD set)
CIC - FSC CIC Map, North America Premium 2010 65 90 2 159 282 (3 DVD set)


Note also the following for those people who do not have X5's:

DVD-High (MK IV):
E46 3 Series
E39 5 Series
E38, E65, E66 7 Series
E83 X3
E85 Z4

DVD-Professional (I-Drive):
E87 1 Series
E90, E91 3 Series
E60, E61 5 Series
E63, E64 6 Series

Is there a part number for
DVD-High (MK IV)

I don't understand your question.

I want to puchase the newest map cd. However I need a part number to find it on the realoem site

Still doesn't make sense. You said MKIV which is a DVD based unit. Now you ask for a map CD?! Do you mean a CD with the operating system (because that is on a CD)? or a CD with the nav database, because that is not on CD, it's on DVD and all the part numbers for it are listed in post #2 above, ad nauseum.