VLISP supports the automatic creation of backup copies of files loaded by the text editor. The actual backup creation occurs when you save the file for the first time. Backup files have the same name as your original file, except the file extension begins with an underscore (_) and is followed by the first two characters of the original extension. For example, the backup file for drawline.lsp would be drawline._ls.
Environment Options
General Options. Choose the Editor
option labeled Backup the File Edited on First Save to turn on
automatic backup. By default, this option is already selected when
you first install VLISP.