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Symbian3/SDK/Source/GUID-6DAF85AD-E412-5823-81C2-FC1755A90A84.dita
changeset 0 89d6a7a84779 
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Symbian3/SDK/Source/GUID-6DAF85AD-E412-5823-81C2-FC1755A90A84.dita	Thu Jan 21 18:18:20 2010 +0000
@@ -0,0 +1,90 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->
+<!-- This component and the accompanying materials are made available under the terms of the License 
+"Eclipse Public License v1.0" which accompanies this distribution, 
+and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->
+<!-- Initial Contributors:
+    Nokia Corporation - initial contribution.
+Contributors: 
+-->
+<!DOCTYPE concept
+  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
+<concept id="GUID-6DAF85AD-E412-5823-81C2-FC1755A90A84" xml:lang="en"><title>What
+are elements</title><shortdesc>This topic describes elements. All items that can be stored in
+the Comms Database are elements. The topic also discusses the structure of
+the unique numeric Id and the attributes that control access to elements. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
+<p>An element is represented by the <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>CMDBElement</apiname></xref> class.
+The class is a base class for all items that can be stored in the Comms Database.
+The class contains the data that is common to all items that can be stored
+in the Comms database. </p>
+<p>Elements contain three pieces of information: </p>
+<ul>
+<li id="GUID-42CDC895-ADD7-53E1-86C8-BDCA97874D80"><p>a unique numeric Id
+that defines the location of the element in the database. The Id defines the
+meaning of the element in the database schema as a specific Table, Column,
+Record or Field. A numeric Id also allows for fast access and retrieval of
+an element. </p> </li>
+<li id="GUID-370BB127-A262-561F-BB53-CFD71D7EF61E"><p>a set of attributes
+that controls access to the data. </p> </li>
+<li id="GUID-F533113D-25EF-5CAE-8AA4-FF05CA8894B6"><p>a value that can be
+a single numeric type, a Boolean type, a descriptor, or a composite of one
+or more nested elements. </p> </li>
+</ul>
+<p> <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>CMDBElement</apiname></xref> derives from <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>MMetaDatabase</apiname></xref>. <codeph>MMetaDatabase</codeph> provides
+the behaviour that allows an element to operate with the Comms Database. [See
+accessing the database or words to that effect.] </p>
+<fig id="GUID-3FE9490C-8766-5F31-9147-7F20A03BBF2D">
+<image href="GUID-4B7FA629-BFC9-594B-B253-AC920EAD6E67_d0e65850_href.png" placement="inline"/>
+</fig>
+<section id="GUID-4DDD4947-D379-5B68-8DC0-B67B074FA852"><title>The Element
+Id</title> <p>The <codeph>iElementId</codeph> data member of <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>CMDBElement</apiname></xref> is
+a 32 bit number that contains: </p> <ul>
+<li id="GUID-4F41A6A2-79FC-5CA7-AC9C-B242D7DC925E"><p>the unique numeric Id
+that shows the location of the element in the database. This numeric Id is
+known as the Element Id. </p> </li>
+<li id="GUID-D8EFDBE9-A897-56F8-939A-E3942FCC34F2"><p>the set of attributes
+that controls access to the data. The bits define the access levels. </p> </li>
+</ul> <p>Both pieces of information are encoded in the 32 bit number. The
+32 bit number is a <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>TMDBElementId</apiname></xref> type. </p> <p>The <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>CMDBElement</apiname></xref> class provides member functions to
+access and to change the information in the Element Id. </p></section>
+<section> <p id="GUID-32E556BC-55C3-5FBD-9A60-9708139C20D6"><b>The unique
+numeric Id</b> </p> <p>The unique numeric Id has two parts: the Type Id and
+the Record Id. </p> <p>The Type Id defines the type of element; the Record
+Id identifies an instance of this type of element. </p> <p>The class <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>CMDBElement</apiname></xref> provides the member functions <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>CommsDat::CMDBElement::TypeId()</apiname></xref> and <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>CommsDat::CMDBElement::RecordId()</apiname></xref> to
+extract this information. </p> <p>Internally, the Type Id includes a 8 bit
+number and a 7 bit number. The 8 bit number is the Table Id and the 7 bit
+number is the Column Id. The Type Id and the Record Id are in defined locations
+in the 32 bit number <codeph>iElementId</codeph>. </p> <fig id="GUID-B3A732DF-8D24-532C-A4AB-D5B42408D832">
+<image href="GUID-0B151FE8-21E1-58A1-BEB3-5502EDF052C0_d0e65930_href.png" placement="inline"/>
+</fig> <p>The header file <filepath>comsdat.h</filepath> contains the constants
+that define the location of these Ids in the 32 bit number: </p> <table id="GUID-1369F999-F42E-5268-AF6F-0D5C9A362878">
+<tgroup cols="2"><colspec colname="col0"/><colspec colname="col1"/>
+<tbody>
+<row>
+<entry><p>Table Id </p> </entry>
+<entry><p> <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>KCDMaskShowRecordType</apiname></xref>  </p> </entry>
+</row>
+<row>
+<entry><p>Column Id </p> </entry>
+<entry><p> <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>KCDMaskShowFieldType</apiname></xref>  </p> </entry>
+</row>
+<row>
+<entry><p>Type Id </p> </entry>
+<entry><p> <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>KCDMaskShowType</apiname></xref>  </p> </entry>
+</row>
+<row>
+<entry><p>Record Id </p> </entry>
+<entry><p> <xref href="GUID-1CDD0B97-8B00-3373-9908-512C9BC1CF51.dita"><apiname>KCDMaskShowRecordId</apiname></xref>  </p> </entry>
+</row>
+</tbody>
+</tgroup>
+</table> </section>
+<section><p id="GUID-EE8E5985-4159-5780-8001-E51EB4821D05"><b> The set of
+attributes that controls access to the data</b> </p><p>The access levels of
+an element are defined by the bits in the element. The <xref href="GUID-2AF9DED8-0AAE-370B-8FA2-B2910939A7B8.dita"><apiname>TCDAttributeFlags</apiname></xref> enum
+defines the access levels of an element. These bits are stored in the fourth
+byte of the <codeph>iElementId</codeph> member of <xref href="GUID-C36F41FE-1776-3735-89F3-DAAAFA7FDC91.dita"><apiname>CMDBElement</apiname></xref>. </p><fig id="GUID-A1C2FF44-AA19-42B8-8F10-E927170A317A">
+<image href="GUID-46673FC4-ADA9-59D1-A743-B4784425D240_d0e66039_href.png" placement="inline"/>
+</fig><p> <xref href="GUID-DC185E84-1DC0-36F7-9B3D-19B4B3E641D7.dita"><apiname>KCDMaskShowAttributes</apiname></xref> in the header file <filepath>comsdat.h</filepath> defines
+the location of these access control bits in the 32 bit number.</p>  </section>
+</conbody></concept>
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MCL/sftools/depl/docscontent