Proposed resolution:

Add a footnote to [complex.ops] p16:

[In a locale in which comma is being used as a decimal point character, inserting showpoint into the output stream forces all outputs to show an explicit decimal point character; then all inserted complex sequences will extract unambiguously.]

[ Post-Sophia Antipolis: ]

I neglected to pull this issue from the formal motions page after the "showbase" to "showpoint" change. In Sophia Antipolis this change was reviewed by the LWG and the issue was set to Ready. We subsequently voted the footnote into the WP with "showbase".

I'm changing from WP back to Ready to pick up the "showbase" to "showpoint" change.

[ Pre-Sophia Antipolis, Howard adds: ]

Changed "showbase" to "showpoint" and changed from Ready to Review.

[ Bellevue: ]

After much discussion, we agreed on the following: Add a footnote:

[In a locale in which comma is being used as a decimal point character, inserting "showbase" into the output stream forces all outputs to show an explicit decimal point character; then all inserted complex sequences will extract unambiguously.]

And move this to READY status.

is there an issue opened for (0,3) as complex number with the French local? With the English local, the above parses as an imaginery complex number. With the French locale it parses as a real complex number.

Further notes/ideas from the lib-reflector, messages 17982-17984:

Add additional entries in num_punct to cover the complex separator (French would be ';').

Insert a space before the comma, which should eliminate the ambiguity.

Solve the problem for ordered sequences in general, perhaps with a dedicated facet. Then complex should use that solution.