further details.
Within the ASCII range (U+0001..U+007F), the valid characters for identifiers
-are the same as in Python 2.x: the uppercase and lowercase letters ``A`` through
+include the uppercase and lowercase letters ``A`` through
``Z``, the underscore ``_`` and, except for the first character, the digits
``0`` through ``9``.
-
-Python 3.0 introduces additional characters from outside the ASCII range (see
+Python 3.0 introduced additional characters from outside the ASCII range (see
:pep:`3131`). For these characters, the classification uses the version of the
Unicode Character Database as included in the :mod:`unicodedata` module.