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 Detailed Description of `ed' Format
 ...................................
 
    The `ed' output format consists of one or more hunks of differences.
 The changes closest to the ends of the files come first so that
 commands that change the number of lines do not affect how `ed'
 interprets line numbers in succeeding commands.  `ed' format hunks look
 like this:
 
      CHANGE-COMMAND
      TO-FILE-LINE
      TO-FILE-LINE...
      .
 
    Because `ed' uses a single period on a line to indicate the end of
 input, GNU `diff' protects lines of changes that contain a single
 period on a line by writing two periods instead, then writing a
 subsequent `ed' command to change the two periods into one.  The `ed'
 format cannot represent an incomplete line, so if the second file ends
 in a changed incomplete line, `diff' reports an error and then pretends
 that a newline was appended.
 
    There are three types of change commands.  Each consists of a line
 number or comma-separated range of lines in the first file and a single
 character indicating the kind of change to make.  All line numbers are
 the original line numbers in the file.  The types of change commands
 are:
 
 `La'
      Add text from the second file after line L in the first file.  For
      example, `8a' means to add the following lines after line 8 of file
      1.
 
 `Rc'
      Replace the lines in range R in the first file with the following
      lines.  Like a combined add and delete, but more compact.  For
      example, `5,7c' means change lines 5-7 of file 1 to read as the
      text file 2.
 
 `Rd'
      Delete the lines in range R from the first file.  For example,
      `5,7d' means delete lines 5-7 of file 1.
 
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