7.3.3.1. The "ftp" and "tftp" access-types

An access-type of FTP or TFTP indicates that the message body is accessible as a file using the FTP [RFC-959] or TFTP [RFC-783] protocols, respectively. For these access-types, the following additional parameters are mandatory:

      NAME -- The name of the file that contains the actual body data.

      SITE -- A machine from which the file may be obtained, using the
      given protocol. This must be a fully qualified domain name, not a
      nickname.

Before any data are retrieved, using FTP, the user will generally need to be asked to provide a login id and a password for the machine named by the site parameter. For security reasons, such an id and password are not specified as content-type parameters, but must be obtained from the user.

In addition, the following parameters are optional:

      DIRECTORY -- A directory from which the data named by NAME should
      be retrieved.

      MODE -- A case-insensitive string indicating the mode to be used
      when retrieving the information.  The legal values for access-type
      "TFTP" are "NETASCII", "OCTET", and "MAIL", as specified by the
      TFTP protocol [RFC-783].  The legal values for access-type "FTP"
      are "ASCII", "EBCDIC", "IMAGE", and "LOCALn" where "n" is a
      decimal integer, typically 8.  These correspond to the
      representation types "A" "E" "I" and "L n" as specified by the FTP
      protocol [RFC-959].  Note that "BINARY" and "TENEX" are not valid
      values for MODE, but that "OCTET" or "IMAGE" or "LOCAL8" should be
      used instead.  IF MODE is not specified, the default value is
      "NETASCII" for TFTP and "ASCII" otherwise.