Searched and didn't find anything easily, until I came across this. Its a good reference, and I thought I should post it with easily searchable terms.

2000 AUDI S4 (With HID (high intensity discharge) headlamps) -----

Low beam headlamp
HID-D2S

High beam headlamp
H7

Parking light
2886X
3457ALL

Front turn signal
2827
3457ALL

Rear turn signal
7506

Tail light
7528

Stop light
7528

High mount stop light
2825

Fog/Driving light
H7

License plate
6418

Back up light
7506

Front sidemarker
3457ALL

Rear sidemarker
2825

Glove box
6418

Map light
64111

Dome light
6411

Step/Courtesy light
2825
6418

Trunk/Cargo area
6418

Under hood light
6411