set defaultfilter= filterstring

This command specifies the default list of file types to display in the Filter menu (or pull-down) on the Open dialog box.

filterstring specifies a list of file types separated by a vertical bar “|”. There are two parts to each item, which are also separated by a vertical bar “|”. The first part is the string to display in the menu or pop-up menu. The second part is the corresponding pattern to use to filter the files displayed in the dialog box. Multiple patterns may be specified by separating them with a semicolon.

Example