+Perl uses "full" Unicode case mappings. This means that converting a single
+character to another case may result in a sequence of more than one character.
+For example, the uppercase of C<E<223>> (LATIN SMALL LETTER SHARP S) is the two
+character sequence C<SS>. This presents some complications The lowercase of
+all characters in the range 0..255 is a single character, and thus
+C<L</toLOWER_L1>> is furnished. But, C<toUPPER_L1> can't exist, as it couldn't
+return a valid result for all legal inputs. Instead C<L</toUPPER_uvchr>> has
+an API that does allow every possible legal result to be returned.) Likewise
+no other function that is crippled by not being able to give the correct
+results for the full range of possible inputs has been implemented here.
+
+=for apidoc Am|U8|toUPPER|U8 ch
+Converts the specified character to uppercase. If the input is anything but an
+ASCII lowercase character, that input character itself is returned. Variant
+C<toUPPER_A> is equivalent.
+
+=for apidoc Am|UV|toUPPER_uvchr|UV cp|U8* s|STRLEN* lenp
+Converts the code point C<cp> to its uppercase version, and
+stores that in UTF-8 in C<s>, and its length in bytes in C<lenp>. The code
+point is interpreted as native if less than 256; otherwise as Unicode. Note
+that the buffer pointed to by C<s> needs to be at least C<UTF8_MAXBYTES_CASE+1>
+bytes since the uppercase version may be longer than the original character.
+
+The first code point of the uppercased version is returned
+(but note, as explained at L<the top of this section|/Character case
+changing>, that there may be more.)
+
+=for apidoc Am|UV|toUPPER_utf8_safe|U8* p|U8* e|U8* s|STRLEN* lenp
+Converts the first UTF-8 encoded character in the sequence starting at C<p> and
+extending no further than S<C<e - 1>> to its uppercase version, and
+stores that in UTF-8 in C<s>, and its length in bytes in C<lenp>. Note
+that the buffer pointed to by C<s> needs to be at least C<UTF8_MAXBYTES_CASE+1>
+bytes since the uppercase version may be longer than the original character.
+
+The first code point of the uppercased version is returned
+(but note, as explained at L<the top of this section|/Character case
+changing>, that there may be more).
+
+The suffix C<_safe> in the function's name indicates that it will not attempt
+to read beyond S<C<e - 1>>, provided that the constraint S<C<s E<lt> e>> is
+true (this is asserted for in C<-DDEBUGGING> builds). If the UTF-8 for the
+input character is malformed in some way, the program may croak, or the
+function may return the REPLACEMENT CHARACTER, at the discretion of the
+implementation, and subject to change in future releases.
+
+=for apidoc Am|UV|toUPPER_utf8|U8* p|U8* s|STRLEN* lenp
+This is like C<L</toUPPER_utf8_safe>>, but doesn't have the C<e>
+parameter The function therefore can't check if it is reading
+beyond the end of the string. Starting in Perl v5.30, it will take the C<e>
+parameter, becoming a synonym for C<toUPPER_utf8_safe>. At that time every
+program that uses it will have to be changed to successfully compile. In the
+meantime, the first runtime call to C<toUPPER_utf8> from each call point in the
+program will raise a deprecation warning, enabled by default. You can convert
+your program now to use C<toUPPER_utf8_safe>, and avoid the warnings, and get an
+extra measure of protection, or you can wait until v5.30, when you'll be forced
+to add the C<e> parameter.
+
+=for apidoc Am|U8|toFOLD|U8 ch
+Converts the specified character to foldcase. If the input is anything but an
+ASCII uppercase character, that input character itself is returned. Variant
+C<toFOLD_A> is equivalent. (There is no equivalent C<to_FOLD_L1> for the full
+Latin1 range, as the full generality of L</toFOLD_uvchr> is needed there.)
+
+=for apidoc Am|UV|toFOLD_uvchr|UV cp|U8* s|STRLEN* lenp
+Converts the code point C<cp> to its foldcase version, and
+stores that in UTF-8 in C<s>, and its length in bytes in C<lenp>. The code
+point is interpreted as native if less than 256; otherwise as Unicode. Note
+that the buffer pointed to by C<s> needs to be at least C<UTF8_MAXBYTES_CASE+1>
+bytes since the foldcase version may be longer than the original character.
+
+The first code point of the foldcased version is returned
+(but note, as explained at L<the top of this section|/Character case
+changing>, that there may be more).
+
+=for apidoc Am|UV|toFOLD_utf8_safe|U8* p|U8* e|U8* s|STRLEN* lenp
+Converts the first UTF-8 encoded character in the sequence starting at C<p> and
+extending no further than S<C<e - 1>> to its foldcase version, and
+stores that in UTF-8 in C<s>, and its length in bytes in C<lenp>. Note
+that the buffer pointed to by C<s> needs to be at least C<UTF8_MAXBYTES_CASE+1>
+bytes since the foldcase version may be longer than the original character.
+
+The first code point of the foldcased version is returned
+(but note, as explained at L<the top of this section|/Character case
+changing>, that there may be more).
+
+The suffix C<_safe> in the function's name indicates that it will not attempt
+to read beyond S<C<e - 1>>, provided that the constraint S<C<s E<lt> e>> is
+true (this is asserted for in C<-DDEBUGGING> builds). If the UTF-8 for the
+input character is malformed in some way, the program may croak, or the
+function may return the REPLACEMENT CHARACTER, at the discretion of the
+implementation, and subject to change in future releases.
+
+=for apidoc Am|UV|toFOLD_utf8|U8* p|U8* s|STRLEN* lenp
+This is like C<L</toFOLD_utf8_safe>>, but doesn't have the C<e>
+parameter The function therefore can't check if it is reading
+beyond the end of the string. Starting in Perl v5.30, it will take the C<e>
+parameter, becoming a synonym for C<toFOLD_utf8_safe>. At that time every
+program that uses it will have to be changed to successfully compile. In the
+meantime, the first runtime call to C<toFOLD_utf8> from each call point in the
+program will raise a deprecation warning, enabled by default. You can convert
+your program now to use C<toFOLD_utf8_safe>, and avoid the warnings, and get an
+extra measure of protection, or you can wait until v5.30, when you'll be forced
+to add the C<e> parameter.
+
+=for apidoc Am|U8|toLOWER|U8 ch
+Converts the specified character to lowercase. If the input is anything but an
+ASCII uppercase character, that input character itself is returned. Variant
+C<toLOWER_A> is equivalent.
+
+=for apidoc Am|U8|toLOWER_L1|U8 ch
+Converts the specified Latin1 character to lowercase. The results are
+undefined if the input doesn't fit in a byte.
+
+=for apidoc Am|U8|toLOWER_LC|U8 ch
+Converts the specified character to lowercase using the current locale's rules,
+if possible; otherwise returns the input character itself.
+
+=for apidoc Am|UV|toLOWER_uvchr|UV cp|U8* s|STRLEN* lenp
+Converts the code point C<cp> to its lowercase version, and
+stores that in UTF-8 in C<s>, and its length in bytes in C<lenp>. The code
+point is interpreted as native if less than 256; otherwise as Unicode. Note
+that the buffer pointed to by C<s> needs to be at least C<UTF8_MAXBYTES_CASE+1>
+bytes since the lowercase version may be longer than the original character.
+
+The first code point of the lowercased version is returned
+(but note, as explained at L<the top of this section|/Character case
+changing>, that there may be more).
+
+
+=for apidoc Am|UV|toLOWER_utf8_safe|U8* p|U8* e|U8* s|STRLEN* lenp
+Converts the first UTF-8 encoded character in the sequence starting at C<p> and
+extending no further than S<C<e - 1>> to its lowercase version, and
+stores that in UTF-8 in C<s>, and its length in bytes in C<lenp>. Note
+that the buffer pointed to by C<s> needs to be at least C<UTF8_MAXBYTES_CASE+1>
+bytes since the lowercase version may be longer than the original character.
+
+The first code point of the lowercased version is returned
+(but note, as explained at L<the top of this section|/Character case
+changing>, that there may be more).
+
+The suffix C<_safe> in the function's name indicates that it will not attempt
+to read beyond S<C<e - 1>>, provided that the constraint S<C<s E<lt> e>> is
+true (this is asserted for in C<-DDEBUGGING> builds). If the UTF-8 for the
+input character is malformed in some way, the program may croak, or the
+function may return the REPLACEMENT CHARACTER, at the discretion of the
+implementation, and subject to change in future releases.
+
+=for apidoc Am|UV|toLOWER_utf8|U8* p|U8* s|STRLEN* lenp
+This is like C<L</toLOWER_utf8_safe>>, but doesn't have the C<e>
+parameter The function therefore can't check if it is reading
+beyond the end of the string. Starting in Perl v5.30, it will take the C<e>
+parameter, becoming a synonym for C<toLOWER_utf8_safe>. At that time every
+program that uses it will have to be changed to successfully compile. In the
+meantime, the first runtime call to C<toLOWER_utf8> from each call point in the
+program will raise a deprecation warning, enabled by default. You can convert
+your program now to use C<toLOWER_utf8_safe>, and avoid the warnings, and get an
+extra measure of protection, or you can wait until v5.30, when you'll be forced
+to add the C<e> parameter.
+
+=for apidoc Am|U8|toTITLE|U8 ch
+Converts the specified character to titlecase. If the input is anything but an
+ASCII lowercase character, that input character itself is returned. Variant
+C<toTITLE_A> is equivalent. (There is no C<toTITLE_L1> for the full Latin1
+range, as the full generality of L</toTITLE_uvchr> is needed there. Titlecase is
+not a concept used in locale handling, so there is no functionality for that.)
+
+=for apidoc Am|UV|toTITLE_uvchr|UV cp|U8* s|STRLEN* lenp
+Converts the code point C<cp> to its titlecase version, and
+stores that in UTF-8 in C<s>, and its length in bytes in C<lenp>. The code
+point is interpreted as native if less than 256; otherwise as Unicode. Note
+that the buffer pointed to by C<s> needs to be at least C<UTF8_MAXBYTES_CASE+1>
+bytes since the titlecase version may be longer than the original character.
+
+The first code point of the titlecased version is returned
+(but note, as explained at L<the top of this section|/Character case
+changing>, that there may be more).
+
+=for apidoc Am|UV|toTITLE_utf8_safe|U8* p|U8* e|U8* s|STRLEN* lenp
+Converts the first UTF-8 encoded character in the sequence starting at C<p> and
+extending no further than S<C<e - 1>> to its titlecase version, and
+stores that in UTF-8 in C<s>, and its length in bytes in C<lenp>. Note
+that the buffer pointed to by C<s> needs to be at least C<UTF8_MAXBYTES_CASE+1>
+bytes since the titlecase version may be longer than the original character.
+
+The first code point of the titlecased version is returned
+(but note, as explained at L<the top of this section|/Character case
+changing>, that there may be more).
+
+The suffix C<_safe> in the function's name indicates that it will not attempt
+to read beyond S<C<e - 1>>, provided that the constraint S<C<s E<lt> e>> is
+true (this is asserted for in C<-DDEBUGGING> builds). If the UTF-8 for the
+input character is malformed in some way, the program may croak, or the
+function may return the REPLACEMENT CHARACTER, at the discretion of the
+implementation, and subject to change in future releases.
+
+=for apidoc Am|UV|toTITLE_utf8|U8* p|U8* s|STRLEN* lenp
+This is like C<L</toLOWER_utf8_safe>>, but doesn't have the C<e>
+parameter The function therefore can't check if it is reading
+beyond the end of the string. Starting in Perl v5.30, it will take the C<e>
+parameter, becoming a synonym for C<toTITLE_utf8_safe>. At that time every
+program that uses it will have to be changed to successfully compile. In the
+meantime, the first runtime call to C<toTITLE_utf8> from each call point in the
+program will raise a deprecation warning, enabled by default. You can convert
+your program now to use C<toTITLE_utf8_safe>, and avoid the warnings, and get an
+extra measure of protection, or you can wait until v5.30, when you'll be forced
+to add the C<e> parameter.