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7.4 KiB
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177 lines
7.4 KiB
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML>
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<HEAD>
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<META HTTP-EQUIV="CONTENT-TYPE" CONTENT="text/html; charset=utf-8">
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<TITLE>"PTHREAD_SPIN_DESTROY"(P) manual page</TITLE>
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<META NAME="GENERATOR" CONTENT="OpenOffice.org 1.1.3 (Linux)">
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<META NAME="CREATED" CONTENT="20050505;12074100">
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<META NAME="CHANGED" CONTENT="20050505;19014200">
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<!-- manual page source format generated by PolyglotMan v3.2, -->
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</HEAD>
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<BODY LANG="en-GB" BGCOLOR="#ffffff" DIR="LTR">
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<H4>POSIX Threads for Windows – REFERENCE - <A HREF="http://sources.redhat.com/pthreads-win32">Pthreads-w32</A></H4>
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<P><A HREF="index.html">Reference Index</A></P>
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<P><A HREF="#toc">Table of Contents</A></P>
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<H2><A HREF="#toc0" NAME="sect0">Name</A></H2>
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<P>pthread_spin_destroy, pthread_spin_init - destroy or initialize a
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spin lock object (<B>ADVANCED REALTIME THREADS</B>)
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</P>
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<H2><A HREF="#toc1" NAME="sect1">Synopsis</A></H2>
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<P><B>#include <pthread.h> </B>
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</P>
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<P><B>pthread_spinlock_t</B> <I>lock</I> <B>=
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PTHREAD_SPINLOCK_INITIALIZER;</B></P>
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<P><B>int pthread_spin_destroy(pthread_spinlock_t *</B><I>lock</I><B>);
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<BR>int pthread_spin_init(pthread_spinlock_t *</B><I>lock</I><B>, int</B>
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<I>pshared</I><B>); </B>
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</P>
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<H2><A HREF="#toc2" NAME="sect2">Description</A></H2>
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<P>The <B>pthread_spin_destroy</B> function shall destroy the spin
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lock referenced by <I>lock</I> and release any resources used by the
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lock. The effect of subsequent use of the lock is undefined until the
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lock is reinitialized by another call to <B>pthread_spin_init</B> .
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The results are undefined if <B>pthread_spin_destroy</B> is called
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when a thread holds the lock, or if this function is called with an
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uninitialized thread spin lock.
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</P>
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<P>The <B>pthread_spin_init</B> function shall allocate any resources
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required to use the spin lock referenced by <I>lock</I> and
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initialize the lock to an unlocked state.
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</P>
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<P><B>Pthreads-w32</B> supports single and multiple processor systems
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as well as process CPU affinity masking by checking the mask when the
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spin lock is initialized. If the process is using only a single
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processor at the time <B>pthread_spin_init</B> is called then the
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spin lock is initialized as a PTHREAD_MUTEX_NORMAL mutex object. A
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thread that calls <A HREF="pthread_spin_lock.html"><B>pthread_spin_lock(3)</B></A>
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will block rather than spin in this case. If the process CPU affinity
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mask is altered after the spin lock has been initialised, the spin
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lock is not modified, and may no longer be optimal for the number of
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CPUs available.</P>
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<P><B>Pthreads-w32</B> defines <B>_POSIX_THREAD_PROCESS_SHARED</B> in
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pthread.h as -1 to indicate that these routines do not support the
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<B>PTHREAD_PROCESS_SHARED</B> attribute. <B>pthread_spin_init</B>
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will return the error <B>ENOTSUP</B> if the value of <I>pshared</I>
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is not <B>PTHREAD_PROCESS_PRIVATE</B>.</P>
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<P>The results are undefined if <B>pthread_spin_init</B> is called
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specifying an already initialized spin lock. The results are
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undefined if a spin lock is used without first being initialized.
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</P>
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<P>If the <B>pthread_spin_init</B> function fails, the lock is not
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initialized and the contents of <I>lock</I> are undefined.
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</P>
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<P>Only the object referenced by <I>lock</I> may be used for
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performing synchronization.
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</P>
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<P>The result of referring to copies of that object in calls to
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<B>pthread_spin_destroy</B> , <A HREF="pthread_spin_lock.html"><B>pthread_spin_lock</B>(3)</A>
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, <A HREF="pthread_spin_lock.html"><B>pthread_spin_trylock</B>(3)</A>,
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or <A HREF="pthread_spin_unlock.html"><B>pthread_spin_unlock</B>(3)</A>
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is undefined.
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</P>
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<P><B>Pthreads-w32</B> supports statically initialized spin locks
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using <B>PTHREAD_SPINLOCK_INITIALIZER</B>. An application should
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still call <B>pthread_spin_destroy</B> at some point to ensure that
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any resources consumed by the spin lock are released.</P>
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<H2><A HREF="#toc3" NAME="sect3">Return Value</A></H2>
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<P>Upon successful completion, these functions shall return zero;
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otherwise, an error number shall be returned to indicate the error.
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</P>
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<H2><A HREF="#toc4" NAME="sect4">Errors</A></H2>
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<P>These functions may fail if:
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</P>
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<DL>
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<DT><B>EBUSY</B>
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</DT><DD>
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The implementation has detected an attempt to initialize or destroy
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a spin lock while it is in use (for example, while being used in a
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<A HREF="pthread_spin_lock.html"><B>pthread_spin_lock</B>(3)</A>
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call) by another thread.
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</DD><DT>
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<B>EINVAL</B>
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</DT><DD STYLE="margin-bottom: 0.5cm">
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The value specified by <I>lock</I> is invalid.
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</DD></DL>
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<P>
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The <B>pthread_spin_init</B> function shall fail if:
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</P>
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<DL>
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<DT><B>ENOTSUP</B>
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</DT><DD>
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The value of <I>pshared</I> is not <B>PTHREAD_PROCESS_PRIVATE</B>.</DD><DT>
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<B>ENOMEM</B>
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</DT><DD STYLE="margin-bottom: 0.5cm">
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Insufficient memory exists to initialize the lock.
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</DD></DL>
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<P>
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These functions shall not return an error code of [EINTR].
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</P>
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<P><I>The following sections are informative.</I>
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</P>
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<H2><A HREF="#toc5" NAME="sect5">Examples</A></H2>
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<P>None.
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</P>
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<H2><A HREF="#toc6" NAME="sect6">Application Usage</A></H2>
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<P>The <B>pthread_spin_destroy</B> and <B>pthread_spin_init</B>
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functions are part of the Spin Locks option and need not be provided
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on all implementations.
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</P>
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<H2><A HREF="#toc7" NAME="sect7">Rationale</A></H2>
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<P>None.
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</P>
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<H2><A HREF="#toc8" NAME="sect8">Future Directions</A></H2>
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<P>None.
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</P>
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<H2><A HREF="#toc9" NAME="sect9">See Also</A></H2>
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<P><A HREF="pthread_spin_lock.html"><B>pthread_spin_lock</B>(3)</A> <B>,</B>
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<A HREF="pthread_spin_unlock.html"><B>pthread_spin_unlock</B>(3)</A>
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<B>,</B> the Base Definitions volume of IEEE Std 1003.1-2001,
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<I><pthread.h></I>
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</P>
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<H2><A HREF="#toc10" NAME="sect10">Copyright</A></H2>
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<P>Portions of this text are reprinted and reproduced in electronic
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form from IEEE Std 1003.1, 2003 Edition, Standard for Information
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Technology -- Portable Operating System Interface (POSIX), The Open
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Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the
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Institute of Electrical and Electronics Engineers, Inc and The Open
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Group. In the event of any discrepancy between this version and the
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original IEEE and The Open Group Standard, the original IEEE and The
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Open Group Standard is the referee document. The original Standard
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can be obtained online at <A HREF="http://www.opengroup.org/unix/online.html">http://www.opengroup.org/unix/online.html</A>
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.
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</P>
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<P>Modified by Ross Johnson for use with <A HREF="http://sources.redhat.com/pthreads-win32">Pthreads-w32</A>.</P>
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<HR>
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<P><A NAME="toc"></A><B>Table of Contents</B></P>
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<UL>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect0" NAME="toc0">Name</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect1" NAME="toc1">Synopsis</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect2" NAME="toc2">Description</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect3" NAME="toc3">Return
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Value</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect4" NAME="toc4">Errors</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect5" NAME="toc5">Examples</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect6" NAME="toc6">Application
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Usage</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect7" NAME="toc7">Rationale</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect8" NAME="toc8">Future
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Directions</A>
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</P>
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<LI><P STYLE="margin-bottom: 0cm"><A HREF="#sect9" NAME="toc9">See
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Also</A>
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</P>
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<LI><P><A HREF="#sect10" NAME="toc10">Copyright</A>
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</P>
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</UL>
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</BODY>
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</HTML>
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