bug#42384: octal escape sequences old fashioned

[Robert Pluim]

>>>>> On Thu, 16 Jul 2020 08:50:28 +0800, 積丹尼 Dan Jacobson 
>>>>> <jidanni@jidanni.org> said:

    積丹尼> (info "(emacs) Text Display") says:
    積丹尼>       The raw bytes with codes ‘U+0080’ (octal 200) through ‘U+009F’ 
(octal
    積丹尼>    237) are displayed as “octal escape sequences”, with the 
‘escape-glyph’
    積丹尼>    face.  For instance, character code ‘U+0098’ (octal 230) is 
displayed as
    積丹尼>    ‘\230’.  If you change the buffer-local variable ‘ctl-arrow’ to 
‘nil’,
    積丹尼>    the ASCII control characters are also displayed as octal escape
    積丹尼>    sequences instead of caret escape sequences.

    積丹尼> OK but octal is rather old fashioned so the user should be given the
    積丹尼> choice of hex, etc.

    display-raw-bytes-as-hex is a variable defined in `C source code'.
    Its value is t
    Original value was nil

      You can customize this variable.
      This variable was introduced, or its default value was changed, in
      version 26.1 of Emacs.
      Probably introduced at or before Emacs version 26.1.

    Documentation:
    Non-nil means display raw bytes in hexadecimal format.
    The default is to use octal format (200) whereas hexadecimal (x80)
    may be more familiar to users.

(the manual in emacs-27 mentions this)

Robert