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RFC 13 UNKNOWN ARPANET · FILES · MESSAGES

Zero Text Length EOF Message

A proposal to use a zero-text-length message to mark the end of a file.

On rfc-editor.org ↗
PUBLISHED
August 1969
AUTHORS
V. Cerf
STREAM
Legacy
TEXT LENGTH
0
LEADER
32 bits
MARKING
32 bits
CHECKSUM
16 bits
DOI
10.17487/RFC0013

RFC text

Original text · RFC Editor View on rfc-editor.org ↗ 
Network Working Group                                          Vint Cerf
Request for Comments: 13                                       UCLA
                                                          20 August 1969




Referring to NWG/RFC: 11, it appears that file transmissions over
auxiliary connections will require some mechanism to specify "END-OF-
FILE."  It is proposed that a length 0 (zero) message be used for this
purpose.  Figure 1 shows the format:






|<---32 bits--->|<---32 bits--->|<----16 bits---->|<------?------>|
+---------------+---------------+-----------------+---------------+
|    leader     |    marking    |    checksum     |    padding    |
+---------------+---------------+-----------------+---------------+



                                Figure 1

                      Zero Text Length EOF Message




       [ This RFC was put into machine readable form for entry ]
      [ into the online RFC archives by Michael Brunnbauer 1/97 ]

ISO Plain Language

On this page
PROBLEMFile transmissions over auxiliary connections need a way to indicate that no more file data follows.
MECHANISMRFC 13 proposes a message with zero text length and shows a leader, marking, checksum and padding in its format.
THE CATCHThe one-page note proposes an end-of-file signal but does not specify receiver behavior.

§1A Signal for the End of a File

The note refers to RFC 11 and says that file transmissions over auxiliary connections need a way to specify END-OF-FILE. Vint Cerf proposes using a message whose length is zero for this purpose.

The note presents this as a proposal and gives a diagram of the message format.

A file transfer needs a clear way to say that no more text is coming. The proposal uses a message with zero text length as that signal.

§1Format of the Empty Message

The figure shows a 32-bit leader, a 32-bit marking, a 16-bit checksum and a padding field whose width is shown as unknown. The text length is zero, but the message still contains these other fields.

The document does not define what the fields mean or give a fixed padding size.

The message carries no text, but it still has other fields, including a checksum. The figure does not state how wide the padding field is.

§1What the Proposal Leaves Unspecified

RFC 13 is a one-page proposal that refers to RFC 11 for the context of auxiliary-connection file transfers. It does not explain how a receiver should react to the zero-length message or describe error handling.

The note suggests the signal and shows its layout. It does not say what the receiving computer should do next.