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<concept id="GUID-AB705D21-87A3-5F32-A4B9-17B7593DD5C3" xml:lang="en"><title>UID
Manipulation Overview</title><shortdesc>Describes how globally unique identifiers are manipulated.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<section id="GUID-78302F5A-97C3-4B95-9F72-842D91C2C25C"><title>Purpose</title> <p>To guarantee uniqueness,
all UID values are assigned to developers centrally by Symbian. </p> </section>
<section id="GUID-0600181A-2383-419B-BB57-2833C05F9AE3"><title>Architectural relationships</title> <p>Symbian platform makes
extensive use of UIDs to provide lightweight identification of file types.
This includes both document and executable files. APIs that need to manipulate
files therefore typically use UIDs.</p> </section>
<section id="GUID-B4652BA6-A500-4F3E-9AFF-02C339706B2B"><title>Description</title> <p>The API has two key concepts: UID and
compound identifier. </p> <p><b>UID</b> </p> <p>The
UID is a small wrapper class around a 32-bit value that provides comparison
operators and conversion to text.</p> <p>The UID interface is provided by <xref href="GUID-530281E6-29FC-33F2-BC9B-610FBA389444.dita"><apiname>TUid</apiname></xref>.</p> <p><b>Compound identifier</b> </p> <p>The compound identifier is a group of
up to three UIDs that identify the type of a file. The meaning of the UIDs
varies according to whether the file is a DLL, or document file, etc. </p> <p>The
compound identifier interface is provided by <xref href="GUID-B6D6B0AD-B15C-339A-8540-40540885089A.dita"><apiname>TUidType</apiname></xref>.</p> </section>
<section id="GUID-ECF8B994-B8F0-4EC4-8CE8-06F031541D79"><title>See also</title> <p><xref href="GUID-260C7ACD-0024-59DE-B1C6-0C852E44C457.dita">Dynamically
Loading Link Libraries Overview</xref> </p> <p><xref href="GUID-B69FE02E-3A78-5438-BA7C-F7BB4CD3EB76.dita">File
Server Client Side Overview</xref> </p> <p><xref href="GUID-21CF1D5F-44C5-5407-B3C9-8BC103C97079.dita">File
Stores Overview</xref> </p> </section>
</conbody></concept>