SG16 will hold a telecon on Wednesday, January 26th at 19:30 UTC
(timezone conversion
<https://www.timeanddate.com/worldclock/converter.html?iso=20220126T193000&p1=1440&p2=tz_pst&p3=tz_mst&p4=tz_cst&p5=tz_est&p6=tz_cet>).

The agenda is:

  * P2286R5: Formatting Ranges <https://wg21.link/p2286r5>
      o Review proposed wording for new SG16 concerns and consistency
        with prior guidance.

Barry may not be able to attend this week depending on things happening
that are outside of his control. We'll still review in that case in
order to identify a list of concerns to address, but will not poll
direction in his absence (we could still poll on whether something is or
is not a concern worth addressing, but I don't anticipate such polls).

We last reviewed a draft of P2286R4 <https://wg21.link/p2286r4> during
the 2021-12-15 SG16 telecon
<https://github.com/sg16-unicode/sg16-meetings/blob/master/README-2021.md#december-15th-2021>
where we approved forwarding it to LEWG despite the absence of wording.
Prior to that, we had reviewed P2286R3 <https://wg21.link/p2286r3>
during the 2021-12-01 SG16 telecon
<https://github.com/sg16-unicode/sg16-meetings/blob/master/README-2021.md#december-1st-2021>.
LEWG has since reviewed the proposal during its 2022-01-04 and
2022-01-18 telecons
<https://wiki.edg.com/bin/view/Wg21telecons2022/P2286?twiki_redirect_cache=e1d7621f93ffd926fb2c8172a10fead5>
and has approved forwarding it to electronic polling for C++23. In this
telecon, we'll review the available wording to look for new SG16
concerns and to validate the wording reflects previous design guidance.
Previous design discussion related to the following concerns:

 1. Use of P2290 <https://wg21.link/p2290> style brace delimited
    hexadecimal notation to preserve the values of code units that
    appear in an ill-formed code unit sequence.
 2. Use of P2290 <https://wg21.link/p2290> style brace delimited UCN
    notation (as opposed to hexadecimal notation) for non-printable
    characters.
 3. Whether it is always possible to map an input character to a Unicode
    character for the purpose of determining printability.
 4. How characters are determined to be printable or non-printable.
 5. Handling of lone surrogate characters; whether they are encoded in
    UCN notation (like a non-printable character) or in hexadecimal
    notation (like an invalid code unit).
 6. Handling of unassigned code points.
 7. Handling of Private Use Area (PUA) code points.
 8. How to determine the boundaries of ill-formed code unit sequences.
 9. Whether a replacement character should be emitted for an ill-formed
    code unit sequence (as opposed to emitting hexadecimal notation for
    each contributing code unit).
10. Stability guarantees.
11. Support for non-Unicode platforms.
12. Handling of std::filesystem::path.

Tom.