How do I open a DAT File?

I have a DAT file, and when I open it using Notepad, it has stuff like System.Int32, QSystem.Drawing, System.Drawing.Bitmap, and a bunch of symbols. Which program should I use to open it?
Answer #1
What is the exact Filename*.dat?
DAT Files can be everything, means an Video which can be opened by PowerDVD or an mailed script.
This is going to help you:
http://pcsupport.about.com/od/tipstricks/tp/file_converter.htm
Answer #2
Those names are used in .Net programming. What is filename?
Answer #3
http://pcsupport.about.com/od/fileextensions/f/dat-file.htm
A data file that can be associated with a number of programs.