anchor.diff:      the text entered by the user in response to the `prompt` command
   
   *%val{timestamp}*::
  -    _in buffer scope_ +
  +    _in buffer, window scope_ +
       timestamp of the current buffer, an integer that increments each time the
       buffer is modified, including undoing and redoing previous modifications
       (see also `%val{history_id}`)
  
positive.code:     `%val{bufname}`)
  
  *%val{bufname}*::
      _in buffer scope_ +
      name of the current buffer
  
  *%val{client_env_X}*::
  
negative.code: The following expansions are supported (with required context _in italics_):
  
  *%val{buffile}*::
      _in buffer, window scope_ +
      full path of the file or same as `%val{bufname}` when there’s no
      associated file
  
  *%val{buf_line_count}*::
      _in buffer, window scope_ +
      number of lines in the current buffer
  
  *%val{buflist}*::
  