RFC 5326, "Licklider Transmission Protocol - Specification", September 2008

Errata ID: 1657
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Alfred Hoenes
Date Reported: 2009-01-23
Verifier Name: Stephen Farrell
Date Verified: 2009-11-10

Section 3.1.1, pg.12 says:

   if (CTRL flag = 0)
      segment is a data segment if (EXC flag = 0)
         segment contains only red-part data if (Flag 1 = 1)
            segment is a checkpoint segment is the last segment in the
            red part of the block if (Flag 0 = 1)
               segment is the last segment in the block
         else // segment is not end of red-part
            if (Flag 0 = 1)
               segment is a checkpoint
      else
         segment contains only green-part data if (Flag 1 = 1)
            if (Flag 0 = 1)
               segment is the last segment in the block
   else
      segment is a control segment if (EXC flag = 0)
         segment pertains to report activity if (flag 0 = 0)
            segment is a report segment
         else
            segment is an acknowledgment of a report segment
      else
         segment pertains to session cancellation activity if (Flag 1 =
         0)
            segment pertains to cancellation by block sender if (Flag 0
            = 1)
               segment is a cancellation by sender
            else
               segment is an acknowledgment of a cancellation by sender
         else
            segment pertains to cancellation by block receiver if (Flag
            0 = 1)
               segment is a cancellation by receiver
            else
               segment is an acknowledgment of a cancellation by
               receiver

It should say:

   if (CTRL flag = 0)
      segment is a data segment
      if (EXC flag = 0)
         segment contains only red-part data
         if (Flag 1 = 1)
            segment is a checkpoint
            segment is the last segment in the red part of the block
            if (Flag 0 = 1)
               segment is the last segment in the block
         else // segment is not end of red-part
            if (Flag 0 = 1)
               segment is a checkpoint
      else
         segment contains only green-part data
         if (Flag 1 = 1)
            if (Flag 0 = 1)
               segment is the last segment in the block
   else
      segment is a control segment
      if (EXC flag = 0)
         segment pertains to report activity
         if (flag 0 = 0)
            segment is a report segment
         else
            segment is an acknowledgment of a report segment
      else
         segment pertains to session cancellation activity
         if (Flag 1 = 0)
            segment pertains to cancellation by block sender
|           if (Flag 0 = 0)
               segment is a cancellation by sender
            else
               segment is an acknowledgment of a cancellation by sender
         else
            segment pertains to cancellation by block receiver
|           if (Flag 0 = 0)
               segment is a cancellation by receiver
            else
               segment is an acknowledgment of a cancellation by
               receiver

Notes:

Issues:

a) Confusing placement of line breaks: "if" clauses could be
understood as postfix qualifiers, but in fact shall be prefixes
to subsequent clauses; independent statements should be separated
by line breaks.

Correction: re-formating of entire pseudocode block

b) Sense of "Flag 0" in the "CTRL=1" branches is illogical and inconsistent
with remainder of the RFC -- e.g., cf. sections 3.1.2 and 3.1.3 !

Correction: Change "if (Flag 0 = 1)" --> "if (Flag 0 = 0)"
in the two lines tagged with change bars in the corrected text.

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