Issue #21559: Add alternative (historical) reason for OverflowError.

diff --git a/Doc/library/exceptions.rst b/Doc/library/exceptions.rst
index d2c2ef45976bca28c7e8d7a8de9d37d3797aa4c7..74d6fcb78c273fe71d5c3e627bc110a02bb497be 100644 (file)
--- a/Doc/library/exceptions.rst
+++ b/Doc/library/exceptions.rst
@@ -274,9 +274,10 @@ The following exceptions are the exceptions that are usually raised.
 
    Raised when the result of an arithmetic operation is too large to be
    represented.  This cannot occur for integers (which would rather raise
-   :exc:`MemoryError` than give up).  Because of the lack of standardization of
-   floating point exception handling in C, most floating point operations also
-   aren't checked.
+   :exc:`MemoryError` than give up).  However, for historical reasons,
+   OverflowError is sometimes raised for integers that are outside a required
+   range.   Because of the lack of standardization of floating point exception
+   handling in C, most floating point operations are not checked.
 
 
 .. exception:: ReferenceError