gh-99875: Document rounding mode for old-style formatting (#126382)

diff --git a/Doc/library/stdtypes.rst b/Doc/library/stdtypes.rst
index a70bda47da6f43a8c66bd548f4ac10aaa76bea92..6b55daa9b6eae0c2d63abca13fdba9bca8bb25e7 100644 (file)
--- a/Doc/library/stdtypes.rst
+++ b/Doc/library/stdtypes.rst
@@ -3202,6 +3202,10 @@ The conversion types are:
 |            | character in the result.                            |       |
 +------------+-----------------------------------------------------+-------+
 
+For floating-point formats, the result should be correctly rounded to a given
+precision ``p`` of digits after the decimal point.  The rounding mode matches
+that of the :func:`round` builtin.
+
 Notes:
 
 (1)