It seems that the purpose of blocker is to protect files having file extensions entered in the setting. I originally thought that it protects other files from being created, modified, or deleted by files having file extensions entered in the setting. Then blocker, to me, is no longer useful. It protects those specified files (exe, scr, com…) as well as viruses, worms and trojans. One may draw the conclusion that blocker is a tool to protect viruses, since most viruses have file extensions like exe.