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<concept id="GUID-70E1117B-17F0-5CF4-A5D0-35D3BEBB0FEA" xml:lang="en"><title>Position
Area Data Classes</title><shortdesc>This document describes the basic and extended position area data
classes that contain information about the accuracy of the position returned
to an application when it calls <codeph>RPositioner::GetLastKnownPositionArea()</codeph>. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>LBS maintains a cache of previously calculated position fixes. If an application
calls <xref href="GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575.dita#GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575/GUID-BF3BBDC5-8B12-3374-ACEB-4013E9CFEBEF"><apiname>RPositioner::GetLastKnownLocation()</apiname></xref>, LBS returns
the most recently calculated position. If an application calls <xref href="GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575.dita#GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575/GUID-A8484963-B2C4-339D-AF8C-056792444D89"><apiname>RPositioner::GetLastKnownPositionArea()</apiname></xref>,
LBS returns the position fix that is the best match for the current location
of the mobile device. The current location of the mobile device is estimated
from data received from the network. </p>
<p>The Location Acquisition API defines a set of position area data classes
(figure 1). A client application passes an object of one of these classes
as a parameter when it calls <xref href="GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575.dita#GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575/GUID-A8484963-B2C4-339D-AF8C-056792444D89"><apiname>RPositioner::GetLastKnownPositionArea()</apiname></xref>.
The position area data classes are defined in <filepath>LbsAreaInfo.h</filepath>. </p>
<fig id="GUID-898DA2B8-185E-5906-803A-1871320A0F7E">
<title>           Figure 1. Position Area Data Classes.          </title>
<image href="GUID-4930A22F-EF80-5B08-A878-C0DB73929558_d0e446617_href.png" placement="inline"/>
</fig>
<p>A brief description of the classes follows. Follow the links to more detailed
reference documentation. </p>
<ul>
<li id="GUID-6EFEC1C0-FA51-5700-AF45-C25F69C8FF34"><p> <xref href="GUID-4AD8EC91-7272-3ABA-92AB-E299E85FDC6D.dita"><apiname>TPositionAreaInfoBase</apiname></xref> is
the base class of the position area data classes. Applications create an object
of one of the derived classes. </p> </li>
<li id="GUID-0F54B61E-D87A-5014-8808-863323BBD475"><p> <xref href="GUID-5FA78254-70C7-3105-B6CE-E1A294C8F773.dita"><apiname>TPositionAreaInfo</apiname></xref> contains
basic information about the accuracy of a returned position. Its defines an
enumerated type <xref href="GUID-5FA78254-70C7-3105-B6CE-E1A294C8F773.dita#GUID-5FA78254-70C7-3105-B6CE-E1A294C8F773/GUID-3B9DEDE6-8903-3B26-9CE6-19D6B4833309"><apiname>TPositionAreaInfo::_TArea</apiname></xref> that defines
an estimate of how closely the current device position matches the returned
position. The position accuracy estimate can be from country level down to
street level, depending on how much information is available from the network. </p> </li>
<li id="GUID-7ADA8994-7028-5C76-9870-FB0F4AA82F82"><p> <xref href="GUID-BC7DEDAF-80AE-34DC-8FD8-CF77FA511B3D.dita"><apiname>TPositionAreaExtendedInfo</apiname></xref> extends <codeph>TPositionAreaInfo</codeph> to
provide details about how the accuracy estimate of the returned position was
calculated. </p> <p>An accuracy estimate can be obtained from the network
as some combination of the following: </p> <ul>
<li id="GUID-AA4BFDD9-D024-5F1C-873C-55A18AC7EB10"><p>Mobile Country Code </p> </li>
<li id="GUID-7AEE15CD-33B2-5833-BE64-8E2D2C729DF4"><p>Mobile Network Code </p> </li>
<li id="GUID-4666634D-05C4-59C1-AD51-55A28F67DC3B"><p>Location Area Code </p> </li>
<li id="GUID-B3BEE4FC-8955-5FAC-B382-121F49C8D1D7"><p>Cell ID </p> </li>
</ul> <p>LBS uses combinations of the above to derive the accuracy estimate
returned from <xref href="GUID-5FA78254-70C7-3105-B6CE-E1A294C8F773.dita#GUID-5FA78254-70C7-3105-B6CE-E1A294C8F773/GUID-C8B19BA7-72A0-35CD-AF72-AD74E9C0CE5B"><apiname>TPositionAreaInfo::Area()</apiname></xref>. Your application
can find what types of data were used to calculate the accuracy estimate by
passing an object of class <xref href="GUID-BC7DEDAF-80AE-34DC-8FD8-CF77FA511B3D.dita"><apiname>TPositionAreaExtendedInfo</apiname></xref> to <xref href="GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575.dita#GUID-1EAEB7EF-0AC7-37C7-B35F-C9B780FFC575/GUID-A00A1673-10F2-357A-A3CA-FFB4E14F2F8D"><apiname>RPositioner::GetLastKnownLocationArea()</apiname></xref> and
then using the methods shown in figure 1 to check for code and ID matches. </p> </li>
</ul>
</conbody><related-links>
<link><linktext/></link>
<link href="GUID-F6B5F777-D12F-5913-AECE-047DF8C72F1F.dita"><linktext>How to Get
Location Information</linktext></link>
</related-links></concept>