+=for apidoc isC9_STRICT_UTF8_CHAR
+
+Evaluates to non-zero if the first few bytes of the string starting at C<s> and
+looking no further than S<C<e - 1>> are well-formed UTF-8 that represents some
+Unicode non-surrogate code point; otherwise it evaluates to 0. If non-zero,
+the value gives how many bytes starting at C<s> comprise the code point's
+representation. Any bytes remaining before C<e>, but beyond the ones needed to
+form the first code point in C<s>, are not examined.
+
+The largest acceptable code point is the Unicode maximum 0x10FFFF. This
+differs from C<L</isSTRICT_UTF8_CHAR>> only in that it accepts non-character
+code points. This corresponds to
+L<Unicode Corrigendum #9|http://www.unicode.org/versions/corrigendum9.html>.
+which said that non-character code points are merely discouraged rather than
+completely forbidden in open interchange. See
+L<perlunicode/Noncharacter code points>.
+
+Use C<L</isUTF8_CHAR>> to check for Perl's extended UTF-8; and
+C<L</isUTF8_CHAR_flags>> for a more customized definition.
+
+Use C<L</is_c9strict_utf8_string>>, C<L</is_c9strict_utf8_string_loc>>, and
+C<L</is_c9strict_utf8_string_loclen>> to check entire strings.
+
+=cut
+
+This uses an adaptation of the tables and algorithm given in
+http://bjoern.hoehrmann.de/utf-8/decoder/dfa/, which provides comprehensive
+documentation of the original version. A copyright notice for the original
+version is given at the beginning of this file. The Perl adapation is
+documented at the definition of PL_c9_utf8_dfa_tab[].
+
+*/
+
+PERL_STATIC_INLINE Size_t
+Perl_isC9_STRICT_UTF8_CHAR(const U8 * const s0, const U8 * const e)
+{
+ const U8 * s = s0;
+ UV state = 0;
+
+ PERL_ARGS_ASSERT_ISC9_STRICT_UTF8_CHAR;
+
+ while (s < e && LIKELY(state != 1)) {
+ state = PL_c9_utf8_dfa_tab[256 + state + PL_c9_utf8_dfa_tab[*s]];
+
+ if (state != 0) {
+ s++;
+ continue;
+ }
+
+ return s - s0 + 1;
+ }
+
+ return 0;
+}
+
+/*
+