2002.08.23 15:10 "BMP files with alpha/transparency channel?", by Michael O'Rourke
2002.08.23 21:20 "RE: BMP files with alpha/transparency channel?", by Tore Bostrup
Microsoft uses the concept of a "mask" color to create apparent transparency. However, the transparency is created by the application and is not inherent in the bitmap AFAIK.
HTH,
Tore.