+The Unicode Script and Script_Extensions properties give what script a
+given character is in. Either property can be specified with the
+compound form like
+C<\p{Script=Hebrew}> (short: C<\p{sc=hebr}>), or
+C<\p{Script_Extensions=Javanese}> (short: C<\p{scx=java}>).
+In addition, Perl furnishes shortcuts for all
+C<Script> property names. You can omit everything up through the equals
+(or colon), and simply write C<\p{Latin}> or C<\P{Cyrillic}>.
+(This is not true for C<Script_Extensions>, which is required to be
+written in the compound form.)
+
+The difference between these two properties involves characters that are
+used in multiple scripts. For example the digits '0' through '9' are
+used in many parts of the world. These are placed in a script named
+C<Common>. Other characters are used in just a few scripts. For
+example, the "KATAKANA-HIRAGANA DOUBLE HYPHEN" is used in both Japanese
+scripts, Katakana and Hiragana, but nowhere else. The C<Script>
+property places all characters that are used in multiple scripts in the
+C<Common> script, while the C<Script_Extensions> property places those
+that are used in only a few scripts into each of those scripts; while
+still using C<Common> for those used in many scripts. Thus both these
+match:
+
+ "0" =~ /\p{sc=Common}/ # Matches
+ "0" =~ /\p{scx=Common}/ # Matches
+
+and only the first of these match:
+
+ "\N{KATAKANA-HIRAGANA DOUBLE HYPHEN}" =~ /\p{sc=Common} # Matches
+ "\N{KATAKANA-HIRAGANA DOUBLE HYPHEN}" =~ /\p{scx=Common} # No match
+
+And only the last two of these match:
+
+ "\N{KATAKANA-HIRAGANA DOUBLE HYPHEN}" =~ /\p{sc=Hiragana} # No match
+ "\N{KATAKANA-HIRAGANA DOUBLE HYPHEN}" =~ /\p{sc=Katakana} # No match
+ "\N{KATAKANA-HIRAGANA DOUBLE HYPHEN}" =~ /\p{scx=Hiragana} # Matches
+ "\N{KATAKANA-HIRAGANA DOUBLE HYPHEN}" =~ /\p{scx=Katakana} # Matches
+
+C<Script_Extensions> is thus an improved C<Script>, in which there are
+fewer characters in the C<Common> script, and correspondingly more in
+other scripts. It is new in Unicode version 6.0, and its data are likely
+to change significantly in later releases, as things get sorted out.
+
+(Actually, besides C<Common>, the C<Inherited> script, contains
+characters that are used in multiple scripts. These are modifier
+characters which modify other characters, and inherit the script value
+of the controlling character. Some of these are used in many scripts,
+and so go into C<Inherited> in both C<Script> and C<Script_Extensions>.
+Others are used in just a few scripts, so are in C<Inherited> in
+C<Script>, but not in C<Script_Extensions>.)
+
+It is worth stressing that there are several different sets of digits in
+Unicode that are equivalent to 0-9 and are matchable by C<\d> in a
+regular expression. If they are used in a single language only, they
+are in that language's C<Script> and C<Script_Extension>. If they are
+used in more than one script, they will be in C<sc=Common>, but only
+if they are used in many scripts should they be in C<scx=Common>.