--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Symbian3/SDK/Source/GUID-3BC54F46-5F81-5F2D-ACF8-E8E0A0D5A345.dita	Wed Mar 31 11:11:55 2010 +0100
@@ -0,0 +1,52 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->
+<!-- This component and the accompanying materials are made available under the terms of the License 
+"Eclipse Public License v1.0" which accompanies this distribution, 
+and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->
+<!-- Initial Contributors:
+    Nokia Corporation - initial contribution.
+Contributors: 
+-->
+<!DOCTYPE concept
+  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
+<concept id="GUID-3BC54F46-5F81-5F2D-ACF8-E8E0A0D5A345" xml:lang="en"><title>Handles
+versus File Descriptors</title><prolog><metadata><keywords/></metadata></prolog><conbody>
+<p>STDLIB provides a POSIX-like abstraction of file descriptors which unifies
+the different types of resource and permits a single API to be used across
+all of them. This is a significantly different approach from Win32 and the
+Symbian platform, both of which have separate APIs for each distinct type
+of resource. </p>
+<p>STDLIB supports files stored in the file system, sockets, a console, and
+a <codeph>/dev/null</codeph> device. The first time STDLIB initialises its
+internal file descriptor table it creates an emulated console device and attaches
+it to descriptors 0, 1 and 2. The emulated console device will appear as a
+window when it is first used (i.e. when the program writes to or reads from
+the console). </p>
+<p>The <codeph>open()</codeph> function recognises the following names: </p>
+<ul>
+<li id="GUID-6093ADF0-5171-5ECC-910A-7F1CDCEBA54F"><p> <codeph>CON:</codeph> is
+taken to mean a newly-created console. This will never be the same console
+as the one automatically associated with 0, 1 and 2. </p> </li>
+<li id="GUID-F99DC14D-ABD1-5B2C-BD93-966986F974B8"><p> <codeph>NUL:</codeph> is
+taken to mean a <codeph>/dev/null</codeph> device. </p> </li>
+<li id="GUID-11DF24CF-BF8C-5DBD-87AA-AF667953D8E6"><p> <codeph>TMP:</codeph> is
+taken to mean a temporary file, which will use the underlying Symbian platform
+file system facilities to create a uniquely-named temporary file, and will
+cause the file to be deleted after it has been closed cleanly. </p> </li>
+<li id="GUID-9D55E093-D3CA-5FDA-B32D-918675840C4A"><p> <codeph>COMx:</codeph> is
+the serial port where x is a number from 1 to 9. <codeph>COM1:</codeph> corresponds
+to serial port zero and so on. </p> </li>
+<li id="GUID-96E9F3A9-9A90-5A27-8B2B-50151CBA045B"><p> <codeph>IRCOMx:</codeph> is
+the serial port where x is a number from 1 to 9. </p> </li>
+</ul>
+<p>The number of open files in the file has no explicit limit. </p>
+<p>The Symbian platform resources such as <codeph>RFile</codeph> and <codeph>RSocket</codeph> are
+derived from class <codeph>RSubSessionBase</codeph>, so are thread specific.
+This means they cannot be used by any thread other than the one which opened
+them. In STDLIB however, the <codeph>CPosixServer</codeph>, if running, controls
+the master file descriptor table. In this case, all STDLIB threads in a process
+may share their resources, because the STDLIB implementation forwards all
+I/o requests to the resources owned by that process's <codeph>CPosixServer</codeph> thread.
+If no <codeph>CPosixServer</codeph> is running, each thread has a separate
+file descriptor table and the resources are not shareable. </p>
+</conbody></concept>
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