General information about file extensions
The correct file extension for FreeHand 10 files is .fh10, which follows the pattern of the FreeHand file extension since version 4.

Previous Windows operating systems required that file names conform to an “8.3” naming convention. This convention dictated that a file name have only eight characters for the file name and three characters for the extension.

The three-character limit on file name extensions became obsolete with the introduction of Windows Long File Names (LFN) in Windows NT and Windows 2000. With LFN, file extensions do not have a character limit. The only limitation for the file name is the length of the file’s path, which cannot have more than 255 characters (including drive letter and punctuation). Note that many extensions used by Windows in a default installation (before any applications are installed) are four to six characters long.