Improve vertical spacing of documentation markup
This commit is contained in:
Peter Eisentraut
parent
ae556c4416
commit
ed9330cff5
@ -377,10 +377,13 @@ initdb --locale-provider=icu --icu-locale=en
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variants and customization options.
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</para>
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</sect2>
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<sect2 id="icu-locales">
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<title>ICU Locales</title>
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<sect3 id="icu-locale-names">
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<title>ICU Locale Names</title>
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<para>
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The ICU format for the locale name is a <link
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linkend="icu-language-tag">Language Tag</link>.
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@ -412,16 +415,19 @@ NOTICE: using standard form "de-DE" for locale "de_DE.utf8"
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linkend="icu-language-tag">language tag</link> instead of relying on the
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transformation.
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</para>
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<para>
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A locale with no language name, or the special language name
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<literal>root</literal>, is transformed to have the language
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<literal>und</literal> ("undefined").
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</para>
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<para>
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ICU can transform most libc locale names, as well as some other formats,
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into language tags for easier transition to ICU. If a libc locale name is
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used in ICU, it may not have precisely the same behavior as in libc.
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</para>
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<para>
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If there is a problem interpreting the locale name, or if the locale name
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represents a language or region that ICU does not recognize, you will see
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@ -442,10 +448,12 @@ CREATE COLLATION
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<sect3 id="icu-language-tag">
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<title>Language Tag</title>
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<para>
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A language tag, defined in BCP 47, is a standardized identifier used to
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identify languages, regions, and other information about a locale.
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</para>
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<para>
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Basic language tags are simply
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<replaceable>language</replaceable><literal>-</literal><replaceable>region</replaceable>;
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@ -457,6 +465,7 @@ CREATE COLLATION
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<literal>ja-JP</literal>, <literal>de</literal>, or
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<literal>fr-CA</literal>.
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</para>
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<para>
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Collation settings may be included in the language tag to customize
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collation behavior. ICU allows extensive customization, such as
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@ -464,6 +473,7 @@ CREATE COLLATION
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treatment of digits within text; and many other options to satisfy a
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variety of uses.
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</para>
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<para>
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To include this additional collation information in a language tag,
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append <literal>-u</literal>, which indicates there are additional
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@ -477,6 +487,7 @@ CREATE COLLATION
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<literal>-</literal><replaceable>value</replaceable>, which implies a
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value of <literal>true</literal>.
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</para>
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<para>
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For example, the language tag <literal>en-US-u-kn-ks-level2</literal>
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means the locale with the English language in the US region, with
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@ -500,6 +511,7 @@ SELECT 'N-45' < 'N-123' COLLATE mycollation5 as result;
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(1 row)
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</screen>
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</para>
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<para>
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See <xref linkend="icu-custom-collations"/> for details and additional
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examples of using language tags with custom collation information for the
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@ -507,6 +519,7 @@ SELECT 'N-45' < 'N-123' COLLATE mycollation5 as result;
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</para>
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</sect3>
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</sect2>
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<sect2 id="locale-problems">
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<title>Problems</title>
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@ -1100,6 +1113,7 @@ CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-tr
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</tip>
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</sect3>
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</sect2>
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<sect2 id="icu-custom-collations">
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<title>ICU Custom Collations</title>
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@ -1129,8 +1143,10 @@ SELECT 'w;x*y-z' = 'wxyz' COLLATE num_ignore_punct; -- true
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linkend="icu-collation-settings"/>, or see <xref
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linkend="icu-external-references"/> for more details.
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</para>
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<sect3 id="icu-collation-comparison-levels">
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<title>ICU Comparison Levels</title>
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<para>
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Comparison of two strings (collation) in ICU is determined by a
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multi-level process, where textual features are grouped into
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@ -1138,6 +1154,7 @@ SELECT 'w;x*y-z' = 'wxyz' COLLATE num_ignore_punct; -- true
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linkend="icu-collation-settings-table">collation settings</link>. Higher
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levels correspond to finer textual features.
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</para>
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<para>
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<xref linkend="icu-collation-levels"/> shows which textual feature
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differences are considered significant when determining equality at the
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@ -1145,7 +1162,7 @@ SELECT 'w;x*y-z' = 'wxyz' COLLATE num_ignore_punct; -- true
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invisible separator, and as seen in the table, is ignored for at all
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levels of comparison less than <literal>identic</literal>.
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</para>
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<para>
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<table id="icu-collation-levels">
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<title>ICU Collation Levels</title>
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<tgroup cols="8">
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@ -1157,6 +1174,7 @@ SELECT 'w;x*y-z' = 'wxyz' COLLATE num_ignore_punct; -- true
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<colspec colname="col6" colwidth="1*"/>
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<colspec colname="col7" colwidth="1*"/>
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<colspec colname="col8" colwidth="1*"/>
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<thead>
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<row>
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<entry>Level</entry>
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@ -1169,6 +1187,7 @@ SELECT 'w;x*y-z' = 'wxyz' COLLATE num_ignore_punct; -- true
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<entry><literal>'y' = 'z'</literal></entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>level1</entry>
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@ -1224,6 +1243,7 @@ SELECT 'w;x*y-z' = 'wxyz' COLLATE num_ignore_punct; -- true
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</tgroup>
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</table>
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<para>
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At every level, even with full normalization off, basic normalization is
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performed. For example, <literal>'á'</literal> may be composed of the
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code points <literal>U&'\0061\0301'</literal> or the single code
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@ -1233,9 +1253,9 @@ SELECT 'w;x*y-z' = 'wxyz' COLLATE num_ignore_punct; -- true
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created with <symbol>deterministic</symbol> set to
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<literal>true</literal>.
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</para>
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<sect4 id="icu-collation-level-examples">
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<title>Collation Level Examples</title>
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<para>
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<programlisting>
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CREATE COLLATION level3 (provider = icu, deterministic = false, locale = 'und-u-ka-shifted-ks-level3');
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@ -1251,18 +1271,18 @@ SELECT 'x-y' = 'x_y' COLLATE level3; -- true
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SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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</programlisting>
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</para>
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</sect4>
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</sect3>
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<sect3 id="icu-collation-settings">
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<title>Collation Settings for an ICU Locale</title>
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<para>
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<xref linkend="icu-collation-settings-table"/> shows the available
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collation settings, which can be used as part of a language tag to
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customize a collation.
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</para>
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<para>
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<table id="icu-collation-settings-table">
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<title>ICU Collation Settings</title>
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<tgroup cols="4">
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@ -1270,6 +1290,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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<colspec colname="col2" colwidth="2*"/>
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<colspec colname="col3" colwidth="2*"/>
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<colspec colname="col4" colwidth="5*"/>
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<thead>
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<row>
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<entry>Key</entry>
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@ -1278,6 +1299,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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<entry>Description</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry><literal>co</literal></entry>
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@ -1287,6 +1309,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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Collation type. See <xref linkend="icu-external-references"/> for additional options and details.
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</entry>
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</row>
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<row>
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<entry><literal>ka</literal></entry>
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<entry><literal>noignore</literal>, <literal>shifted</literal></entry>
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@ -1299,6 +1322,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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character classes are ignored.
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</entry>
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</row>
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<row>
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<entry><literal>kb</literal></entry>
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<entry><literal>true</literal>, <literal>false</literal></entry>
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@ -1309,6 +1333,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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before <literal>'aé'</literal>.
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</entry>
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</row>
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<row>
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<entry><literal>kc</literal></entry>
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<entry><literal>true</literal>, <literal>false</literal></entry>
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@ -1325,6 +1350,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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</para>
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</entry>
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</row>
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<row>
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<entry><literal>kf</literal></entry>
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<entry>
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@ -1339,6 +1365,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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the rules of the locale.
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</entry>
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</row>
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<row>
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<entry><literal>kn</literal></entry>
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<entry><literal>true</literal>, <literal>false</literal></entry>
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@ -1350,6 +1377,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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<literal>'id-123'</literal>.
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</entry>
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</row>
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<row>
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<entry><literal>kk</literal></entry>
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<entry><literal>true</literal>, <literal>false</literal></entry>
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@ -1373,6 +1401,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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</para>
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</entry>
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</row>
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<row>
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<entry><literal>kr</literal></entry>
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<entry>
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@ -1398,6 +1427,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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</para>
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</entry>
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</row>
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<row>
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<entry><literal>ks</literal></entry>
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<entry><literal>level1</literal>, <literal>level2</literal>, <literal>level3</literal>, <literal>level4</literal>, <literal>identic</literal></entry>
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@ -1409,6 +1439,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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<xref linkend="icu-collation-levels"/> for details.
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</entry>
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</row>
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<row>
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<entry><literal>kv</literal></entry>
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<entry>
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@ -1429,10 +1460,13 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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</tbody>
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</tgroup>
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</table>
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Defaults may depend on locale. The above table is not meant to be
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complete. See <xref linkend="icu-external-references"/> for additional
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options and details.
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<para>
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Defaults may depend on locale. The above table is not meant to be
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complete. See <xref linkend="icu-external-references"/> for additional
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options and details.
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</para>
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<note>
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<para>
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For many collation settings, you must create the collation with
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@ -1448,7 +1482,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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<sect3 id="icu-locale-examples">
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<title>Examples</title>
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<para>
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<variablelist>
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<varlistentry id="collation-managing-create-icu-de-u-co-phonebk-x-icu">
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<term><literal>CREATE COLLATION "de-u-co-phonebk-x-icu" (provider = icu, locale = 'de-u-co-phonebk');</literal></term>
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@ -1494,22 +1528,21 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</sect3>
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<sect3 id="icu-external-references">
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<title>External References for ICU</title>
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<para>
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This section (<xref linkend="icu-custom-collations"/>) is only a brief
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overview of ICU behavior and language tags. Refer to the following
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documents for technical details, additional options, and new behavior:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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<ulink
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url="https://www.unicode.org/reports/tr35/tr35-collation.html">Unicode
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Technical Standard #35</ulink>
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<ulink url="https://www.unicode.org/reports/tr35/tr35-collation.html">Unicode Technical Standard #35</ulink>
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</para>
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</listitem>
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<listitem>
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@ -1519,8 +1552,7 @@ SELECT 'x-y' = 'x_y' COLLATE level4; -- false
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</listitem>
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<listitem>
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<para>
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<ulink url="https://github.com/unicode-org/cldr/blob/master/common/bcp47/collation.xml">CLDR
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repository</ulink>
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<ulink url="https://github.com/unicode-org/cldr/blob/master/common/bcp47/collation.xml">CLDR repository</ulink>
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</para>
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</listitem>
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<listitem>
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