anchor.diff:  The following expansions are supported (with required context _in italics_):
   
   *%val{buffile}*::
  -    _in buffer scope_ +
  +    _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 scope_ +
  +    _in buffer, window scope_ +
       number of lines in the current buffer
   
   *%val{buflist}*::
  
positive.code:     width of the current Kakoune window
  
  Values in the above list that do not mention a context are available
  everywhere. Values that mention "buffer scope" are also available in window
  scope.
  
  A value described as a "quoted list" will follow the rules of Kakoune string
  quoting (See <<command-parsing#,`:doc command-parsing`>>). An "unquoted list"
  
negative.code:     the complete parameter string of the executing hook
  
  *%val{modified}*::
      _in buffer, window scope_ +
      `true` if the buffer has modifications not saved, otherwise `false`
  
  *%val{register}*::
  