.xx "a.out" "assembler and link editor output"
.xx "archive" "ar (library) file format"
.xx "ascii" "map of ASCII character set"
.xx "core" "format of core image file"
.xx "dir" "format of directories"
.xx "dump" "incremental dump tape format"
.xx "fs" "format of file system volume"
.xx "greek" "graphics for extended TTY-37 type-box"
.xx "group" "group file"
.xx "mtab" "mounted file system table"
.xx "passwd" "password file"
.xx "tabs" "set tab stops"
.xx "tp" "DEC/mag tape formats"
.xx "ttys" "typewriter initialization data"
.xx "utmp" "user information"
.xx "wtmp" "user login history"
