bpo-31672 - Add one last minor clarification for idpattern (#4483)

Add one last minor clarification for idpattern

1 files changed, 4 insertions, 2 deletions

diff --git a/Doc/library/string.rst b/Doc/library/string.rst
index 5b25428525..e9606783ef 100644
--- a/Doc/library/string.rst
+++ b/Doc/library/string.rst
@@ -755,13 +755,15 @@ attributes:
 
 * *idpattern* -- This is the regular expression describing the pattern for
   non-braced placeholders.  The default value is the regular expression
-  ``(?-i:[_a-zA-Z][_a-zA-Z0-9]*)``.  If this is given and *braceidpattern* is
+  ``(?a:[_a-zA-Z][_a-zA-Z0-9]*)``.  If this is given and *braceidpattern* is
   ``None`` this pattern will also apply to braced placeholders.
 
   .. note::
 
      Since default *flags* is ``re.IGNORECASE``, pattern ``[a-z]`` can match
-     with some non-ASCII characters. That's why we use local ``-i`` flag here.
+     with some non-ASCII characters. That's why we use the local ``a`` flag
+     here.  Further, with the default *flags* value, including ``A-Z`` in the
+     ranges is redundant, but required for backward compatibility.
 
      While *flags* is kept to ``re.IGNORECASE`` for backward compatibility,
      you can override it to ``0`` or ``re.IGNORECASE | re.ASCII`` when