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1 <?xml version="1.0" encoding="utf-8"?> |
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2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. --> |
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3 <!-- This component and the accompanying materials are made available under the terms of the License |
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4 "Eclipse Public License v1.0" which accompanies this distribution, |
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5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". --> |
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6 <!-- Initial Contributors: |
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7 Nokia Corporation - initial contribution. |
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8 Contributors: |
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9 --> |
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10 <!DOCTYPE concept |
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11 PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
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12 <concept id="GUID-A0E21681-F1EF-4E79-965A-040AC7D72A01" xml:lang="en"><title>Time zone conversion overview</title><prolog><metadata><keywords/></metadata></prolog><conbody> |
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13 <p>This document describes the Symbian platform time zone conversion |
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14 component.</p> |
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15 <p/> |
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16 <section id="GUID-17E41393-8170-4FA6-B09C-E07A581CF79A"><title>About |
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17 time zones and daylight saving time</title><p><b>Time zones </b></p><p>Time zones are regions that have adopted the same standard time. |
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18 All time zones are defined relative to UTC (Coordinated Universal |
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19 Time) which is the international time standard. See <xref format="html" href="http://www.ghcc.msfc.nasa.gov/utc.html" scope="external">http://www.ghcc.msfc.nasa.gov/utc.html</xref> for |
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20 more details. </p>The time for a location is given relative to UTC. |
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21 For example:<ul> |
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22 <li><p>Mumbai, India: UTC + 5:30 (For example, if it is 12:00 UTC, |
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23 then it is 17:30 in Mumbai) </p></li> |
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24 <li><p>Tokyo, Japan: UTC + 9 (For example, if it is 12:00 UTC, then |
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25 it is 21:00 in Tokyo)</p></li> |
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26 </ul><note>The local time may need to be adjusted due to the use of |
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27 a daylight saving time offset. </note><p>The list of time zones used |
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28 within a country are found in Time zone list. Select a country to |
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29 view all the time zones used within that country. The time zones follow |
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30 a "Location/Area" format, with "Location" being a continent or geographic |
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31 region of the world and "Area" being a time zone region within that |
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32 location, for example, "Europe/Vienna". </p><p><b>Local time</b></p><p>The local time is the time according to the local time zone (the |
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33 place where the phone user is physically located). The local time |
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34 is sometimes referred to as "wall clock" time. </p><p>If local time |
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35 is 10:00 hours in the US Eastern time zone, then the local time in |
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36 the US Pacific time zone is 07:00 hours. This is because US Eastern |
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37 Time is 4 hours behind UTC (UTC -4) and US Pacific Time is 7 hours |
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38 behind UTC (UTC –7 ). </p><p>If a phone user’s normal location is |
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39 in the US Eastern time zone, and travels to a location in the US Pacific |
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40 time zone, the phone time zone should be changed to US Pacific Time. |
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41 </p><p>The system time zone is the time zone to which the device |
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42 is set.</p> </section> |
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43 <section id="GUID-80A22B2A-2ABE-4E8B-B4E3-FDAC586F0B9B"><title>Time |
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44 zone conversion</title><p>The time zone component allows you to set |
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45 the system time zone and to convert time between UTC and any time, |
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46 past, present or future, for any time zone, as long as a rule exists |
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47 for the conversion. The change rules include when to change to and |
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48 from daylight saving time for each time zone. </p><p>The time zone |
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49 rules are provided in a Symbian-native database which is created from |
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50 Olson’s TZ database. It can be configured by device manufacturers |
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51 to save space. The time zone rules for the current time zone are cached |
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52 by the time zone server so that they are quicker to access for future |
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53 conversions. </p><p>Using the time zone component you can do the |
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54 following: </p><ul> |
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55 <li><p>configure the current local time zone.</p></li> |
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56 <li><p>convert a UTC time to the local time for the system time zone.</p></li> |
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57 <li><p>convert a UTC time to the local time for a time zone provided |
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58 by the user.</p></li> |
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59 <li><p>convert the local time for the system time zone to UTC.</p></li> |
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60 <li><p>convert the local time for any time zone provided by the user |
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61 to UTC.</p></li> |
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62 </ul><p>The key classes involved are <codeph>CTzId</codeph>, <codeph>RTz</codeph> and <codeph>CTzConverter</codeph>. </p><fig id="GUID-E9AB8158-B0A4-47FA-A9C2-23E697B04433"> |
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63 <title>Class diagram for Time zone Conversion</title> |
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64 <image href="GUID-CE7DA679-D441-4843-A81B-2A60440B50E8_d0e146989_href.png" placement="inline"/> |
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65 </fig><p><b> See also</b></p><ul> |
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66 <li><p><xref href="GUID-DF4D7DFF-ECA9-40CF-9F3B-4BBC3F8162E4.dita">Converting |
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67 between UTC and local time</xref></p></li> |
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68 </ul></section> |
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69 </conbody></concept> |