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<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_d0e79196_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_d0e79276_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_d0e79385_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>