wait wait wait, im dizzy. First the notepad have the extension *.txt, if windows detect an archive with this extension, then will open the file with the notepad (or other program if you changued this in the options). Information about the file extensions can be foun in this page:
http://filext.com/
That is a good one.
Now you can changue very easy one *.txt file in other kind of file. Many kind of files are writted in single text file and the only think that you need for changue one file from one kind to other kind, is just changue the extension. In that way you can convert one *.txt file in for example a web page *.htm just changuin the extension. This is the way in that i eddit my web page. Now there is a list of file extensions that i know that work perfectly if you changue the file extensions.
autorun.txt-----------autorun. i n f (information about the autorun of a Cd, or flash disc)
system.txt------------system. b a t (Windows start modify only if you know what are you doing)
start.txt----------------start. h t m (web page)
command.txt--------command. s y c (systat command file)
And this is not limited to *.txt files, the paintbrush bitmaps can be transformed to icons *.ico changuin only the extension, the icon can be in any size and will keep a tranparent color.
Now try an experiment, changue the extension of a *.bmp file to *.txt, you can see the code of the pixel color, try this with a black and white draw and a color draw, not try doing a small strip in the draw. This is funny but you musn´t save the file and return it to bmp, because the draw don´t will be usefull any more, for a reason that i don´t know you can´t modify *.exe, *.bmp, *.doc, *.xls, and other different files in the notepad, and you can´t returnit to his functional state if you changue something, no matter that you leave the file in his old state