How do i add a "null byte" to the end of a file?

[dbzkid]

i was wondering how would i do this, i was reading up on some forums and they said something about like adding a null byte to a file that would check the checksum of the file. i know that null means nothing, byte is a measurement on computers (how big a file takes up), dun know what checksum is. can anyone care to explain?

 

[Celegorm]

Are they talking adding that to like a MS Word file, or a programming file?

 

[dbzkid]

actually they were talking about legality they said that if people dont want you to share files you can edit the code (im assuming hex) to change the check sum and it will be legal to actually transfer the files
http://endlessparadigm.com/forum/showthread.php?tid=7853&pid=101023#pid101023