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    10 <!DOCTYPE concept

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    12 <concept id="GUID-70E1117B-17F0-5CF4-A5D0-35D3BEBB0FEA" xml:lang="en"><title>Position

    13 Area Data Classes</title><shortdesc>This document describes the basic and extended position area data

    14 classes that contain information about the accuracy of the position returned

    15 to an application when it calls <codeph>RPositioner::GetLastKnownPositionArea()</codeph>. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    16 <p>LBS maintains a cache of previously calculated position fixes. If an application

    17 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

    18 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>,

    19 LBS returns the position fix that is the best match for the current location

    20 of the mobile device. The current location of the mobile device is estimated

    21 from data received from the network. </p>

    22 <p>The Location Acquisition API defines a set of position area data classes

    23 (figure 1). A client application passes an object of one of these classes

    24 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>.

    25 The position area data classes are defined in <filepath>LbsAreaInfo.h</filepath>. </p>

    26 <fig id="GUID-898DA2B8-185E-5906-803A-1871320A0F7E">

    27 <title>           Figure 1. Position Area Data Classes.          </title>

    28 <image href="GUID-4930A22F-EF80-5B08-A878-C0DB73929558_d0e270258_href.png" placement="inline"/>

    29 </fig>

    30 <p>A brief description of the classes follows. Follow the links to more detailed

    31 reference documentation. </p>

    32 <ul>

    33 <li id="GUID-6EFEC1C0-FA51-5700-AF45-C25F69C8FF34"><p> <xref href="GUID-4AD8EC91-7272-3ABA-92AB-E299E85FDC6D.dita"><apiname>TPositionAreaInfoBase</apiname></xref> is

    34 the base class of the position area data classes. Applications create an object

    35 of one of the derived classes. </p> </li>

    36 <li id="GUID-0F54B61E-D87A-5014-8808-863323BBD475"><p> <xref href="GUID-5FA78254-70C7-3105-B6CE-E1A294C8F773.dita"><apiname>TPositionAreaInfo</apiname></xref> contains

    37 basic information about the accuracy of a returned position. Its defines an

    38 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

    39 an estimate of how closely the current device position matches the returned

    40 position. The position accuracy estimate can be from country level down to

    41 street level, depending on how much information is available from the network. </p> </li>

    42 <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

    43 provide details about how the accuracy estimate of the returned position was

    44 calculated. </p> <p>An accuracy estimate can be obtained from the network

    45 as some combination of the following: </p> <ul>

    46 <li id="GUID-AA4BFDD9-D024-5F1C-873C-55A18AC7EB10"><p>Mobile Country Code </p> </li>

    47 <li id="GUID-7AEE15CD-33B2-5833-BE64-8E2D2C729DF4"><p>Mobile Network Code </p> </li>

    48 <li id="GUID-4666634D-05C4-59C1-AD51-55A28F67DC3B"><p>Location Area Code </p> </li>

    49 <li id="GUID-B3BEE4FC-8955-5FAC-B382-121F49C8D1D7"><p>Cell ID </p> </li>

    50 </ul> <p>LBS uses combinations of the above to derive the accuracy estimate

    51 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

    52 can find what types of data were used to calculate the accuracy estimate by

    53 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

    54 then using the methods shown in figure 1 to check for code and ID matches. </p> </li>

    55 </ul>

    56 </conbody><related-links>

    57 <link><linktext/></link>

    58 <link href="GUID-F6B5F777-D12F-5913-AECE-047DF8C72F1F.dita"><linktext>How to Get

    59 Location Information</linktext></link>

    60 </related-links></concept>