You don't need to register file format extensions, usually it's standardized by usage. The common ones are recognized by your operating system but applications

You don't need to register file format extensions, usually it's standardized by usage. The common ones are recognized by your operating system but applications you install ask the system the application with certain file formats. For example on windows here is how the file type associations are done with an installer : http://msdn.microsoft.com/en-us/library/k3bb4tfd(VS.80).aspx http://msdn.microsoft.com/en-us/library/k3bb4tfd(VS.80).aspx (look for the heading creating a file association)