by edge » Mar 14, 2006 @ 1:51pm
It doesn't matter with which extension you save your file, although it is recommended to pick an extension which represents the type of your file.
When using your own extension, try to create an extension which isn't widely used (you can also use .dat or .bin as an extension, which are commonly used for all type of data files). However, the extension doesn't change the data within the file, only which program starts it when double clicking on it in Windows.