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				99	<h1>The Asterix Data Model (ADM)</h1>
				100	<div class="section">
				101	<h2><a name="Table_of_Contents"></a><a name="toc" id="toc">Table of Contents</a></h2>
				102	<ul>
				103
				104	<li><a href="#PrimitiveTypes">Primitive Types</a>
				105	<ul>
				106
				107	<li><a href="#PrimitiveTypesBoolean">Boolean</a></li>
				108	<li><a href="#PrimitiveTypesString">String</a></li>
				109	<li><a href="#PrimitiveTypesInt">Tinyint / Smallint / Integer (Int) / Bigint</a></li>
				110	<li><a href="#PrimitiveTypesFloat">Float</a></li>
				111	<li><a href="#PrimitiveTypesDouble">Double (Double Precision)</a></li>
				112	<li><a href="#PrimitiveTypesBinary">Binary</a></li>
				113	<li><a href="#PrimitiveTypesPoint">Point</a></li>
				114	<li><a href="#PrimitiveTypesLine">Line</a></li>
				115	<li><a href="#PrimitiveTypesRectangle">Rectangle</a></li>
				116	<li><a href="#PrimitiveTypesCircle">Circle</a></li>
				117	<li><a href="#PrimitiveTypesPolygon">Polygon</a></li>
				118	<li><a href="#PrimitiveTypesDate">Date</a></li>
				119	<li><a href="#PrimitiveTypesTime">Time</a></li>
				120	<li><a href="#PrimitiveTypesDateTime">Datetime (Timestamp)</a></li>
				121	<li><a href="#PrimitiveTypesDuration">Duration/Year_month_duration/Day_time_duration</a></li>
				122	<li><a href="#PrimitiveTypesInterval">Interval</a></li>
				123	<li><a href="#PrimitiveTypesUUID">UUID</a></li>
				124	</ul>
				125	</li>
				126	<li><a href="#IncompleteInformationTypes">Incomplete Information Types</a>
				127	<ul>
				128
				129	<li><a href="#IncompleteInformationTypesNull">Null</a></li>
				130	<li><a href="#IncompleteInformationTypesMissing">Missing</a></li>
				131	</ul>
				132	</li>
				133	<li><a href="#DerivedTypes">Derived Types</a>
				134	<ul>
				135
				136	<li><a href="#DerivedTypesObject">Object</a></li>
				137	<li><a href="#DerivedTypesArray">Array</a></li>
				138	<li><a href="#DerivedTypesMultiset">Multiset</a></li>
				139	</ul>
				140	</li>
				141	</ul>
				142	<p>An instance of Asterix data model (ADM) can be a <i><i>primitive type</i></i> (<tt>boolean</tt>, <tt>tinyint</tt>, <tt>smallint</tt>, <tt>integer</tt>, <tt>bigint</tt>, <tt>string</tt>, <tt>float</tt>, <tt>double</tt>, <tt>date</tt>, <tt>time</tt>, <tt>datetime</tt>, etc.), a <i><i>special type</i></i> (<tt>null</tt> or <tt>missing</tt>), or a <i><i>derived type</i></i>.</p>
				143	<p>The type names are case-insensitive, e.g., both <tt>BIGINT</tt> and <tt>bigint</tt> are acceptable.</p><!--
				144	! Licensed to the Apache Software Foundation (ASF) under one
				145	! or more contributor license agreements. See the NOTICE file
				146	! distributed with this work for additional information
				147	! regarding copyright ownership. The ASF licenses this file
				148	! to you under the Apache License, Version 2.0 (the
				149	! "License"); you may not use this file except in compliance
				150	! with the License. You may obtain a copy of the License at
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				153	!
				154	! Unless required by applicable law or agreed to in writing,
				155	! software distributed under the License is distributed on an
				156	! "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
				157	! KIND, either express or implied. See the License for the
				158	! specific language governing permissions and limitations
				159	! under the License.
				160	!-->
				161	</div>
				162	<div class="section">
				163	<h2><a name="Primitive_Types"></a><a name="PrimitiveTypes" id="PrimitiveTypes">Primitive Types</a></h2>
				164	<div class="section">
				165	<h3><a name="Boolean"></a><a name="PrimitiveTypesBoolean" id="PrimitiveTypesBoolean">Boolean</a></h3>
				166	<p><tt>boolean</tt> data type can have one of the two values: <i>true</i> or <i>false</i>.</p>
				167	<ul>
				168
				169	<li>
				170
				171	<p>Example:</p>
				172
				173	<div>
				174	<div>
				175	<pre class="source">{ "true": true, "false": false };
				176	</pre></div></div>
				177	</li>
				178	<li>
				179
				180	<p>The expected result is:</p>
				181
				182	<div>
				183	<div>
				184	<pre class="source">{ "true": true, "false": false }
				185	</pre></div></div>
				186	</li>
				187	</ul></div>
				188	<div class="section">
				189	<h3><a name="String"></a><a name="PrimitiveTypesString" id="PrimitiveTypesString">String</a></h3>
				190	<p><tt>string</tt> represents a sequence of characters. The total length of the sequence can be up to 2,147,483,648.</p>
				191	<ul>
				192
				193	<li>
				194
				195	<p>Example:</p>
				196
				197	<div>
				198	<div>
				199	<pre class="source">{ "v1": string("This is a string."), "v2": string("\"This is a quoted string\"") };
				200	</pre></div></div>
				201	</li>
				202	<li>
				203
				204	<p>The expected result is:</p>
				205
				206	<div>
				207	<div>
				208	<pre class="source">{ "v1": "This is a string.", "v2": "\"This is a quoted string\"" }
				209	</pre></div></div>
				210	</li>
				211	</ul><!--
				212	! Licensed to the Apache Software Foundation (ASF) under one
				213	! or more contributor license agreements. See the NOTICE file
				214	! distributed with this work for additional information
				215	! regarding copyright ownership. The ASF licenses this file
				216	! to you under the Apache License, Version 2.0 (the
				217	! "License"); you may not use this file except in compliance
				218	! with the License. You may obtain a copy of the License at
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				220	! http://www.apache.org/licenses/LICENSE-2.0
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				223	! software distributed under the License is distributed on an
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				225	! KIND, either express or implied. See the License for the
				226	! specific language governing permissions and limitations
				227	! under the License.
				228	!-->
				229	</div>
				230	<div class="section">
				231	<h3><a name="Tinyint_.2F_Smallint_.2F_Integer_.28Int.29_.2F_Bigint"></a><a name="PrimitiveTypesInt" id="PrimitiveTypesInt">Tinyint / Smallint / Integer (Int) / Bigint</a></h3>
				232	<p>Integer types using 8, 16, 32, or 64 bits. The ranges of these types are:</p>
				233	<ul>
				234
				235	<li><tt>tinyint</tt>: -128 to 127</li>
				236	<li><tt>smallint</tt>: -32768 to 32767</li>
				237	<li><tt>integer</tt>: -2147483648 to 2147483647</li>
				238	<li><tt>bigint</tt>: -9223372036854775808 to 9223372036854775807</li>
				239	</ul>
				240	<p><tt>int</tt> is an abbreviated alias for integer.</p>
				241	<ul>
				242
				243	<li>
				244
				245	<p>Example:</p>
				246
				247	<div>
				248	<div>
				249	<pre class="source">{ "tinyint": tiny("125"), "smallint": smallint("32765"), "integer": 294967295, "bigint": bigint("1700000000000000000")};
				250	</pre></div></div>
				251	</li>
				252	<li>
				253
				254	<p>The expected result is:</p>
				255
				256	<div>
				257	<div>
				258	<pre class="source">{ "tinyint": 125, "smallint": 32765, "integer": 294967295, "bigint": 1700000000000000000 }
				259	</pre></div></div>
				260	</li>
				261	</ul></div>
				262	<div class="section">
				263	<h3><a name="Float"></a><a name="PrimitiveTypesFloat" id="PrimitiveTypesFloat">Float</a></h3>
				264	<p><tt>float</tt> represents approximate numeric data values using 4 bytes. The range of a float value can be from 2^(-149) to (2-2^(-23)·2^(127) for both positive and negative. Beyond these ranges will get <tt>INF</tt> or <tt>-INF</tt>.</p>
				265	<ul>
				266
				267	<li>
				268
				269	<p>Example:</p>
				270
				271	<div>
				272	<div>
				273	<pre class="source">{ "v1": float("NaN"), "v2": float("INF"), "v3": float("-INF"), "v4": float("-2013.5") };
				274	</pre></div></div>
				275	</li>
				276	<li>
				277
				278	<p>The expected result is:</p>
				279
				280	<div>
				281	<div>
				282	<pre class="source">{ "v1": "NaN", "v2": "INF", "v3": "-INF", "v4": -2013.5 }
				283	</pre></div></div>
				284	</li>
				285	</ul></div>
				286	<div class="section">
				287	<h3><a name="Double_.28double_precision.29"></a><a name="PrimitiveTypesDouble" id="PrimitiveTypesDouble">Double (double precision)</a></h3>
				288	<p><tt>double</tt> represents approximate numeric data values using 8 bytes. The range of a double value can be from (2^(-1022)) to (2-2^(-52))·2^(1023) for both positive and negative. Beyond these ranges will get <tt>INF</tt> or <tt>-INF</tt>.</p>
				289	<ul>
				290
				291	<li>
				292
				293	<p>Example:</p>
				294
				295	<div>
				296	<div>
				297	<pre class="source">{ "v1": double("NaN"), "v2": double("INF"), "v3": double("-INF"), "v4": "-2013.593823748327284" };
				298	</pre></div></div>
				299	</li>
				300	<li>
				301
				302	<p>The expected result is:</p>
				303
				304	<div>
				305	<div>
				306	<pre class="source">{ "v1": "NaN", "v2": "INF", "v3": "-INF", "v4": -2013.5938237483274 }
				307	</pre></div></div>
				308	</li>
				309	</ul>
				310	<p><tt>Double precision</tt> is an alias of <tt>double</tt>.</p></div>
				311	<div class="section">
				312	<h3><a name="Binary"></a><a name="PrimitiveTypesBinary" id="PrimitiveTypesBinary">Binary</a></h3>
				313	<p><tt>binary</tt> represents a sequence of bytes. It can be constructed from a <tt>hex</tt> or a <tt>base64</tt> string sequence. The total length of the byte sequence can be up to 2,147,483,648.</p>
				314	<ul>
				315
				316	<li>
				317
				318	<p>Example:</p>
				319
				320	<div>
				321	<div>
				322	<pre class="source">{
				323	"hex1" : hex("ABCDEF0123456789"),
				324	"hex2": hex("abcdef0123456789"),
				325	"base64_1" : base64("0123456789qwertyui+/"),
				326	"base64_2" : base64('QXN0ZXJpeA==')
				327	};
				328	</pre></div></div>
				329	</li>
				330	<li>
				331
				332	<p>The default output format is in <tt>hex</tt> format. Thus, the expected result is:</p>
				333
				334	<div>
				335	<div>
				336	<pre class="source">{
				337	"hex1": hex("ABCDEF0123456789"),
				338	"hex2": hex("ABCDEF0123456789"),
				339	"base64_1": hex("D35DB7E39EBBF3DAB07ABB72BA2FBF"),
				340	"base64_2": hex("41737465726978")
				341	}
				342	</pre></div></div>
				343	</li>
				344	</ul></div>
				345	<div class="section">
				346	<h3><a name="Point"></a><a name="PrimitiveTypesPoint" id="PrimitiveTypesPoint">Point</a></h3>
				347	<p><tt>point</tt> is the fundamental two-dimensional building block for spatial types. It consists of two <tt>double</tt> coordinates x and y.</p>
				348	<ul>
				349
				350	<li>
				351
				352	<p>Example:</p>
				353
				354	<div>
				355	<div>
				356	<pre class="source">{ "v1": point("80.10d, -10E5"), "v2": point("5.10E-10d, -10E5") };
				357	</pre></div></div>
				358	</li>
				359	<li>
				360
				361	<p>The expected result is:</p>
				362
				363	<div>
				364	<div>
				365	<pre class="source">{ "v1": point("80.1,-1000000.0"), "v2": point("5.1E-10,-1000000.0") }
				366	</pre></div></div>
				367	</li>
				368	</ul></div>
				369	<div class="section">
				370	<h3><a name="Line"></a><a name="PrimitiveTypesLine" id="PrimitiveTypesLine">Line</a></h3>
				371	<p><tt>line</tt> consists of two points that represent the start and the end points of a line segment.</p>
				372	<ul>
				373
				374	<li>
				375
				376	<p>Example:</p>
				377
				378	<div>
				379	<div>
				380	<pre class="source">{ "v1": line("10.1234,11.1e-1 +10.2E-2,-11.22"), "v2": line("0.1234,-1.00e-10 +10.5E-2,-01.02") };
				381	</pre></div></div>
				382	</li>
				383	<li>
				384
				385	<p>The expected result is:</p>
				386
				387	<div>
				388	<div>
				389	<pre class="source">{ "v1": line("10.1234,1.11 0.102,-11.22"), "v2": line("0.1234,-1.0E-10 0.105,-1.02") }
				390	</pre></div></div>
				391	</li>
				392	</ul></div>
				393	<div class="section">
				394	<h3><a name="Rectangle"></a><a name="PrimitiveTypesRectangle" id="PrimitiveTypesRectangle">Rectangle</a></h3>
				395	<p><tt>rectangle</tt> consists of two points that represent the <i><i>bottom left</i></i> and <i><i>upper right</i></i> corners of a rectangle.</p>
				396	<ul>
				397
				398	<li>
				399
				400	<p>Example:</p>
				401
				402	<div>
				403	<div>
				404	<pre class="source">{ "v1": rectangle("5.1,11.8 87.6,15.6548"), "v2": rectangle("0.1234,-1.00e-10 5.5487,0.48765") };
				405	</pre></div></div>
				406	</li>
				407	<li>
				408
				409	<p>The expected result is:</p>
				410
				411	<div>
				412	<div>
				413	<pre class="source">{ "v1": rectangle("5.1,11.8 87.6,15.6548"), "v2": rectangle("0.1234,-1.0E-10 5.5487,0.48765") }
				414	</pre></div></div>
				415	</li>
				416	</ul></div>
				417	<div class="section">
				418	<h3><a name="Circle"></a><a name="PrimitiveTypesCircle" id="PrimitiveTypesCircle">Circle</a></h3>
				419	<p><tt>circle</tt> consists of one point that represents the center of the circle and a radius of type <tt>double</tt>.</p>
				420	<ul>
				421
				422	<li>
				423
				424	<p>Example:</p>
				425
				426	<div>
				427	<div>
				428	<pre class="source">{ "v1": circle("10.1234,11.1e-1 +10.2E-2"), "v2": circle("0.1234,-1.00e-10 +10.5E-2") };
				429	</pre></div></div>
				430	</li>
				431	<li>
				432
				433	<p>The expected result is:</p>
				434
				435	<div>
				436	<div>
				437	<pre class="source">{ "v1": circle("10.1234,1.11 0.102"), "v2": circle("0.1234,-1.0E-10 0.105") }
				438	</pre></div></div>
				439	</li>
				440	</ul></div>
				441	<div class="section">
				442	<h3><a name="Polygon"></a><a name="PrimitiveTypesPolygon" id="PrimitiveTypesPolygon">Polygon</a></h3>
				443	<p><tt>polygon</tt> consists of <i><i>n</i></i> points that represent the vertices of a <i><i>simple closed</i></i> polygon.</p>
				444	<ul>
				445
				446	<li>
				447
				448	<p>Example:</p>
				449
				450	<div>
				451	<div>
				452	<pre class="source">{
				453	"v1": polygon("-1.2,+1.3e2 -2.14E+5,2.15 -3.5e+2,03.6 -4.6E-3,+4.81"),
				454	"v2": polygon("-1.0,+10.5e2 -02.15E+50,2.5 -1.0,+3.3e3 -2.50E+05,20.15 +3.5e+2,03.6 -4.60E-3,+4.75 -2,+1.0e2 -2.00E+5,20.10 30.5,03.25 -4.33E-3,+4.75")
				455	};
				456	</pre></div></div>
				457	</li>
				458	<li>
				459
				460	<p>The expected result is:</p>
				461
				462	<div>
				463	<div>
				464	<pre class="source">{
				465	"v1": polygon("-1.2,130.0 -214000.0,2.15 -350.0,3.6 -0.0046,4.81"),
				466	"v2": polygon("-1.0,1050.0 -2.15E50,2.5 -1.0,3300.0 -250000.0,20.15 350.0,3.6 -0.0046,4.75 -2.0,100.0 -200000.0,20.1 30.5,3.25 -0.00433,4.75") }
				467	}
				468	</pre></div></div>
				469	</li>
				470	</ul></div>
				471	<div class="section">
				472	<h3><a name="Date"></a><a name="PrimitiveTypesDate" id="PrimitiveTypesDate">Date</a></h3>
				473	<p><tt>date</tt> represents a time point along the Gregorian calendar system specified by the year, month and day. ASTERIX supports the date from <tt>-9999-01-01</tt> to <tt>9999-12-31</tt>.</p>
				474	<p>A date value can be represented in two formats, extended format and basic format.</p>
				475	<ul>
				476
				477	<li>Extended format is represented as <tt>[-]yyyy-mm-dd</tt> for <tt>year-month-day</tt>. Each field should be padded if there are less digits than the format specified.</li>
				478	<li>Basic format is in the format of <tt>[-]yyyymmdd</tt>.</li>
				479	<li>
				480
				481	<p>Example:</p>
				482
				483	<div>
				484	<div>
				485	<pre class="source">{ "v1": date("2013-01-01"), "v2": date("-19700101") };
				486	</pre></div></div>
				487	</li>
				488	<li>
				489
				490	<p>The expected result is:</p>
				491
				492	<div>
				493	<div>
				494	<pre class="source">{ "v1": date("2013-01-01"), "v2": date("-1970-01-01") }
				495	</pre></div></div>
				496	</li>
				497	</ul></div>
				498	<div class="section">
				499	<h3><a name="Time"></a><a name="PrimitiveTypesTime" id="PrimitiveTypesTime">Time</a></h3>
				500	<p><tt>time</tt> type describes the time within the range of a day. It is represented by three fields: hour, minute and second. Millisecond field is optional as the fraction of the second field. Its extended format is as <tt>hh:mm:ss[.mmm]</tt> and the basic format is <tt>hhmmss[mmm]</tt>. The value domain is from <tt>00:00:00.000</tt> to <tt>23:59:59.999</tt>.</p>
				501	<p>Timezone field is optional for a time value. Timezone is represented as <tt>[+\|-]hh:mm</tt> for extended format or <tt>[+\|-]hhmm</tt> for basic format. Note that the sign designators cannot be omitted. <tt>Z</tt> can also be used to represent the UTC local time. If no timezone information is given, it is UTC by default.</p>
				502	<ul>
				503
				504	<li>
				505
				506	<p>Example:</p>
				507
				508	<div>
				509	<div>
				510	<pre class="source">{ "v1": time("12:12:12.039Z"), "v2": time("000000000-0800") };
				511	</pre></div></div>
				512	</li>
				513	<li>
				514
				515	<p>The expected result is:</p>
				516
				517	<div>
				518	<div>
				519	<pre class="source">{ "v1": time("12:12:12.039Z"), "v2": time("08:00:00.000Z") }
				520	</pre></div></div>
				521	</li>
				522	</ul></div>
				523	<div class="section">
				524	<h3><a name="Datetime_.28Timestamp.29"></a><a name="PrimitiveTypesDateTime" id="PrimitiveTypesDateTime">Datetime (Timestamp)</a></h3>
				525	<p>A <tt>datetime</tt> value is a combination of an <tt>date</tt> and <tt>time</tt>, representing a fixed time point along the Gregorian calendar system. The value is among <tt>-9999-01-01 00:00:00.000</tt> and <tt>9999-12-31 23:59:59.999</tt>.</p>
				526	<p>A <tt>datetime</tt> value is represented as a combination of the representation of its <tt>date</tt> part and <tt>time</tt> part, separated by a separator <tt>T</tt>. Either extended or basic format can be used, and the two parts should be the same format.</p>
				527	<p>Millisecond field and timezone field are optional, as specified in the <tt>time</tt> type.</p>
				528	<ul>
				529
				530	<li>
				531
				532	<p>Example:</p>
				533
				534	<div>
				535	<div>
				536	<pre class="source">{ "v1": datetime("2013-01-01T12:12:12.039Z"), "v2": datetime("-19700101T000000000-0800") };
				537	</pre></div></div>
				538	</li>
				539	<li>
				540
				541	<p>The expected result is:</p>
				542
				543	<div>
				544	<div>
				545	<pre class="source">{ "v1": datetime("2013-01-01T12:12:12.039Z"), "v2": datetime("-1970-01-01T08:00:00.000Z") }
				546	</pre></div></div>
				547	</li>
				548	</ul>
				549	<p><tt>timestamp</tt> is an alias of <tt>datetime</tt>.</p></div>
				550	<div class="section">
				551	<h3><a name="Duration.2FYear_month_duration.2FDay_time_duration"></a><a name="PrimitiveTypesDuration" id="PrimitiveTypesDuration">Duration/Year_month_duration/Day_time_duration</a></h3>
				552	<p><tt>duration</tt> represents a duration of time. A duration value is specified by integers on at least one of the following fields: year, month, day, hour, minute, second, and millisecond.</p>
				553	<p>A duration value is in the format of <tt>[-]PnYnMnDTnHnMn.mmmS</tt>. The millisecond part (as the fraction of the second field) is optional, and when no millisecond field is used, the decimal point should also be absent.</p>
				554	<p>Negative durations are also supported for the arithmetic operations between time instance types (<tt>date</tt>, <tt>time</tt> and <tt>datetime</tt>), and is used to roll the time back for the given duration. For example <tt>date("2012-01-01") + duration("-P3D")</tt> will return <tt>date("2011-12-29")</tt>.</p>
				555	<p>There are also two sub-duration types, namely <tt>year_month_duration</tt> and <tt>day_time_duration</tt>. <tt>year_month_duration</tt> represents only the years and months of a duration, while <tt>day_time_duration</tt> represents only the day to millisecond fields. Different from the <tt>duration</tt> type, both these two subtypes are totally ordered, so they can be used for comparison and index construction.</p>
				556	<p>Note that a canonical representation of the duration is always returned, regardless whether the duration is in the canonical representation or not from the user’s input. More information about canonical representation can be found from <a class="externalLink" href="http://www.w3.org/TR/xpath-functions/#canonical-dayTimeDuration">XPath dayTimeDuration Canonical Representation</a> and <a class="externalLink" href="http://www.w3.org/TR/xpath-functions/#canonical-yearMonthDuration">yearMonthDuration Canonical Representation</a>.</p>
				557	<ul>
				558
				559	<li>
				560
				561	<p>Example:</p>
				562
				563	<div>
				564	<div>
				565	<pre class="source">{ "v1": duration("P100Y12MT12M"), "v2": duration("-PT20.943S") };
				566	</pre></div></div>
				567	</li>
				568	<li>
				569
				570	<p>The expected result is:</p>
				571
				572	<div>
				573	<div>
				574	<pre class="source">{ "v1": duration("P101YT12M"), "v2": duration("-PT20.943S") }
				575	</pre></div></div>
				576	</li>
				577	</ul></div>
				578	<div class="section">
				579	<h3><a name="Interval"></a><a name="PrimitiveTypesInterval" id="PrimitiveTypesInterval">Interval</a></h3>
				580	<p><tt>interval</tt> represents inclusive-exclusive ranges of time. It is defined by two time point values with the same temporal type(<tt>date</tt>, <tt>time</tt> or <tt>datetime</tt>).</p>
				581	<ul>
				582
				583	<li>
				584
				585	<p>Example:</p>
				586
				587	<div>
				588	<div>
				589	<pre class="source">{
				590	"v1": interval(date("2013-01-01"), date("20130505")),
				591	"v2": interval(time("00:01:01"), time("213901049+0800")),
				592	"v3": interval(datetime("2013-01-01T00:01:01"), datetime("20130505T213901049+0800"))
				593	};
				594	</pre></div></div>
				595	</li>
				596	<li>
				597
				598	<p>The expected result is:</p>
				599
				600	<div>
				601	<div>
				602	<pre class="source">{
				603	"v1": interval(date("2013-01-01"), date("2013-05-05")),
				604	"v2": interval(time("00:01:01.000Z"), time("13:39:01.049Z")),
				605	"v3": interval(datetime("2013-01-01T00:01:01.000Z"), datetime("2013-05-05T13:39:01.049Z"))
				606	}
				607	</pre></div></div>
				608	</li>
				609	</ul></div>
				610	<div class="section">
				611	<h3><a name="UUID"></a><a name="PrimitiveTypesUUID" id="PrimitiveTypesUUID">UUID</a></h3>
				612	<p><tt>uuid</tt> represents a UUID value, which stands for Universally unique identifier. It is defined by a canonical format using hexadecimal text with inserted hyphen characters. (E.g.: 5a28ce1e-6a74-4201-9e8f-683256e5706f). This type is generally used to store auto-generated primary key values.</p>
				613	<ul>
				614
				615	<li>
				616
				617	<p>Example:</p>
				618
				619	<div>
				620	<div>
				621	<pre class="source">return { "v1":uuid("5c848e5c-6b6a-498f-8452-8847a2957421") }
				622	</pre></div></div>
				623	</li>
				624	<li>
				625
				626	<p>The expected result is:</p>
				627
				628	<div>
				629	<div>
				630	<pre class="source">{ "v1": uuid("5c848e5c-6b6a-498f-8452-8847a2957421") }
				631	</pre></div></div>
				632	</li>
				633	</ul><!--
				634	! Licensed to the Apache Software Foundation (ASF) under one
				635	! or more contributor license agreements. See the NOTICE file
				636	! distributed with this work for additional information
				637	! regarding copyright ownership. The ASF licenses this file
				638	! to you under the Apache License, Version 2.0 (the
				639	! "License"); you may not use this file except in compliance
				640	! with the License. You may obtain a copy of the License at
				641	!
				642	! http://www.apache.org/licenses/LICENSE-2.0
				643	!
				644	! Unless required by applicable law or agreed to in writing,
				645	! software distributed under the License is distributed on an
				646	! "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
				647	! KIND, either express or implied. See the License for the
				648	! specific language governing permissions and limitations
				649	! under the License.
				650	!-->
				651	</div></div>
				652	<div class="section">
				653	<h2><a name="Incomplete_Information_Types"></a><a name="IncompleteInformationTypes" id="IncompleteInformationTypes">Incomplete Information Types</a></h2>
				654	<div class="section">
				655	<h3><a name="Null"></a><a name="IncompleteInformationTypesNull" id="IncompleteInformationTypesNull">Null</a></h3>
				656	<p><tt>null</tt> is a special value that is often used to represent an unknown value. For example, a user might not be able to know the value of a field and let it be <tt>null</tt>.</p>
				657	<ul>
				658
				659	<li>
				660
				661	<p>Example:</p>
				662
				663	<div>
				664	<div>
				665	<pre class="source">{ "field": null };
				666	</pre></div></div>
				667	</li>
				668	<li>
				669
				670	<p>The expected result is:</p>
				671
				672	<div>
				673	<div>
				674	<pre class="source">{ "field": null }
				675	</pre></div></div>
				676	</li>
				677	</ul></div>
				678	<div class="section">
				679	<h3><a name="Missing"></a><a name="IncompleteInformationTypesMissing" id="IncompleteInformationTypesMissing">Missing</a></h3>
				680	<p><tt>missing</tt> indicates that a name-value pair is missing from an object. If a missing name-value pair is accessed, an empty result value is returned by the query.</p>
				681	<p>As neither the data model nor the system enforces homogeneity for datasets or collections, items in a dataset or collection can be of heterogeneous types and so a field can be present in one object and <tt>missing</tt> in another.</p>
				682	<ul>
				683
				684	<li>
				685
				686	<p>Example:</p>
				687
				688	<div>
				689	<div>
				690	<pre class="source">{ "field": missing };
				691	</pre></div></div>
				692	</li>
				693	<li>
				694
				695	<p>The expected result is:</p>
				696
				697	<div>
				698	<div>
				699	<pre class="source">{ }
				700	</pre></div></div>
				701	</li>
				702	</ul>
				703	<p>Since a field with value <tt>missing</tt> means the field is absent, we get an empty object.</p><!--
				704	! Licensed to the Apache Software Foundation (ASF) under one
				705	! or more contributor license agreements. See the NOTICE file
				706	! distributed with this work for additional information
				707	! regarding copyright ownership. The ASF licenses this file
				708	! to you under the Apache License, Version 2.0 (the
				709	! "License"); you may not use this file except in compliance
				710	! with the License. You may obtain a copy of the License at
				711	!
				712	! http://www.apache.org/licenses/LICENSE-2.0
				713	!
				714	! Unless required by applicable law or agreed to in writing,
				715	! software distributed under the License is distributed on an
				716	! "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
				717	! KIND, either express or implied. See the License for the
				718	! specific language governing permissions and limitations
				719	! under the License.
				720	!-->
				721	</div></div>
				722	<div class="section">
				723	<h2><a name="Derived_Types"></a><a name="DerivedTypes" id="DerivedTypes">Derived Types</a></h2>
				724	<div class="section">
				725	<h3><a name="Object"></a><a name="DerivedTypesObject" id="DerivedTypesObject">Object</a></h3>
				726	<p>An <tt>object</tt> contains a set of ﬁelds, where each ﬁeld is described by its name and type. An object type may be defined as either open or closed. Open objects (instances of open object types) are permitted to contain ﬁelds that are not part of the type deﬁnition, while closed objects do not permit their instances to carry extra fields. An example type definition for an object is:</p>
				727
				728	<div>
				729	<div>
				730	<pre class="source"> create type SoldierType as open {
				731	name: string?,
				732	rank: string,
				733	serialno: int
				734	};
				735	</pre></div></div>
				736
				737	<p>Syntactically, object constructors are surrounded by curly braces “{…}”. Some examples of legitimate instances of the above type include:</p>
				738
				739	<div>
				740	<div>
				741	<pre class="source"> { "name": "Joe Blow", "rank": "Sergeant", "serialno": 1234567 }
				742	{ "rank": "Private", "serialno": 9876543 }
				743	{ "name": "Sally Forth", "rank": "Major", "serialno": 2345678, "gender": "F" }
				744	</pre></div></div>
				745
				746	<p>The first instance has all of the type’s prescribed content. The second instance is missing the name field, which is fine because it is optional (due to the ?). The third instance has an extra field; that is fine because the type definition specifies that it is open (which is also true by default, if open is not specified). To more tightly control object content, specifying closed instead of open in the type definition for SoldierType would have made the third example instance an invalid instance of the type.</p></div>
				747	<div class="section">
				748	<h3><a name="Array"></a><a name="DerivedTypesArray" id="DerivedTypesArray">Array</a></h3>
				749	<p>An <tt>array</tt> is a container that holds a fixed number of values. Array constructors are denoted by brackets: “[…]”.</p>
				750	<p>An example would be</p>
				751
				752	<div>
				753	<div>
				754	<pre class="source"> ["alice", 123, "bob", null]
				755	</pre></div></div>
				756	</div>
				757	<div class="section">
				758	<h3><a name="Multiset"></a><a name="DerivedTypesMultiset" id="DerivedTypesMultiset">Multiset</a></h3>
				759	<p>A <tt>multiset</tt> is a generalization of the concept of a set that, unlike a set, allows multiple instances of the multiset’s elements. Multiset constructors are denoted by two opening curly braces followed by data and two closing curly braces, like “{{…}}”.</p>
				760	<p>An example would be</p>
				761
				762	<div>
				763	<div>
				764	<pre class="source"> {{"hello", 9328, "world", [1, 2, null]}}
				765	</pre></div></div></div></div>
				766	</div>
				767	</div>
				768	</div>
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