Buttonsets:
1 = OK and Cancel buttons
2 = Abort, Retry, and Ignore buttons
3 = Yes, No, and Cancel buttons
4 = Yes and No buttons
5 = Retry and Cancel buttons
Icons:
16 = Critical message icon
32 = Warning Query icon
48 = Warning Message icon
64 = Information Message
Combine buttonsets and icons:
20 = Critical message icon(16) with Yes and No buttons(4)
34 = Warning Query icon(32) with Abort, Retry, and Ignore buttons(2)