Why does Create GUID display different GUID parts with different capitalization?

Visual Studio is shipped with a Create GUID tool that is used for ge开发者_C百科nerating GUIDs. Now here's a GUID it generated for me:

{7A09BF85-9E98-44ea-9AB5-A13953E88C3D}

each of the 4 GUID parts contains both letters and digits. Why does the third part contain only lowercase letters and other only upcase letters? Is there any sence behind that?

See the accepted answer by John Feminella to this question, in which he links to this MS Connect bug report (which, by the way, MS has promised to have solved "in the next release" of VS).