When enabled, anonymous users will only be allowed to download files which are world readable. This is recognising that the ftp user may own files, especially in the presence of uploads.
cmds_allowed
This options specifies a comma separated list of allowed FTP commands (post login. USER, PASS and QUIT are always allowed pre-login). Other commands are rejected. This is a powerful method of really locking down an FTP server. Example: cmds_allowed=PASV,RETR,QUIT