Windows on Windows
Problems with applications running on newer operating systems, especially with long filenames, multiple user accounts, and least privilege, may prohibit some applications from working correctly. For example, they might incorrectly think that they can write files to any part of the file system, but NTFS file permissions exist and does not allow this in many system folders. When Microsoft was building Windows 95, they had to ensure old programs still worked with 8.3 filenames to allow old applications to keep working properly. Since Windows 95, there was a feature where both a long and short file name are kept, so older applications could still use the 8.3 filenames.