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<concept id="GUID-2B7F7484-3A44-4A96-9B5D-79DF8A09115A" xml:lang="en"><title>How resource files work</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>In the Symbian platform, <xref href="GUID-5F749184-C804-41FC-BA81-038783BDC967.dita">resource</xref> files
are used to define UI components used in applications. See <xref href="GUID-0FB60233-993A-4BF2-9E8C-E03AD092359B.dita">Managing resource
files</xref> for information on defining the data structure.</p>
<p>The following resource files are typically used as source files
in Symbian applications:</p>
<ul>
<li><p><codeph>.rss</codeph> – resource source files used
for UI components in the application. For more information, see <xref href="GUID-EC49B54F-7724-433B-BD7F-201DE3B7DAA6.dita">Resource file structure</xref>, <xref href="GUID-23A60DE7-B72D-41BD-9F1E-882D31A7E3C7.dita">Required resource file statements</xref>, and <xref href="GUID-2C74E932-B1CA-434B-AF96-66D52D689620.dita">Optional resource file statements</xref>.</p>
</li>
<li><p><codeph>_reg.rss</codeph> – resource source file
used for registration. For more information, see <xref href="GUID-BF1AAA0D-DF2F-4E1D-A0D2-F419BD32F97A.dita">Creating registration resource files</xref>.</p>
</li>
<li><p><codeph>.hrh</codeph> – resource header file used
to define enumerated sets of values. For more information, see <xref href="GUID-D52E98C3-F5EE-4CE1-A4F5-2EF41A066B8A.dita">Creating resource header files</xref>.</p>
</li>
<li><p><codeph>.rls</codeph> – localization files used as
a source for UI texts strings in applications, and for managing these
texts. For more information, see <xref href="GUID-E111C4E8-1342-4E87-ACB4-5B630AF1501C.dita">Internationalization
and localization</xref>.</p>
</li>
</ul>
<p>The structures and symbolic IDs of the files are used in various
ways in your code.</p>
<p> The resource files above are then compiled to yield the following
files:</p>
<ul>
<li><p><codeph>.rsc</codeph> or <parmname>rNN</parmname>, where NN is a two number Symbian locale ID - compiled, machine-readable
resource files used by the application.</p></li>
<li><p><codeph>.rsg</codeph> - generated resource header
file containing the symbolic IDs of the resources for inclusion into
your code.</p></li>
<li><p><codeph> _reg.rsc</codeph> or <parmname>_reg.rNN</parmname>, where NN is a two number Symbian locale ID - compiled, machine-readable
resource file used for registration .</p></li>
</ul>

<p>The <parmname>rsc</parmname>, <parmname>rNN</parmname>, and <parmname>_reg.rsc</parmname> files
need to be included in your <parmname>.sis</parmname> installation
file so that they are placed in the device when the application is
installed.</p>

<p>When the application framework launches an application, it loads
the application resource file. The application framework compares
the system locale language setting with the available resource files,
and loads the resource file whose extension matches the locale language
code. If there is no match, then the system loads the resource file
with the <parmname>.rsc</parmname>.</p>
</conbody></concept>