xcu_chap01.html

IEEE 1003.1-2003, Single Unix Specification v3

developers are warned not to expect that the output of such an interface on one system is any guide to its behavior on another
system.</p>

<h4><a name="tag_01_08_01"></a>Codes</h4>

<p>Codes and their meanings are listed in the Base Definitions volume of IEEE&nbsp;Std&nbsp;1003.1-2001, but are repeated here for
convenience:</p>

<p><sup>[<a href="javascript:open_code('ADV')">ADV</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Advisory Information <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the ADV margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the ADV margin legend.</p>

<p><sup>[<a href="javascript:open_code('AIO')">AIO</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Asynchronous Input and Output <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the AIO margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the AIO margin legend.</p>

<p><sup>[<a href="javascript:open_code('BAR')">BAR</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Barriers <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the BAR margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the BAR margin legend.</p>

<p><sup>[<a href="javascript:open_code('BE')">BE</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Batch Environment Services and Utilities <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional.</p>

<p>Where applicable, utilities are marked with the BE margin legend in the SYNOPSIS section. Where additional semantics apply to a
utility, the material is identified by use of the BE margin legend.</p>

<p><sup>[<a href="javascript:open_code('CD')">CD</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
C-Language Development Utilities <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional.</p>

<p>Where applicable, utilities are marked with the CD margin legend in the SYNOPSIS section. Where additional semantics apply to a
utility, the material is identified by use of the CD margin legend.</p>

<p><sup>[<a href="javascript:open_code('CPT')">CPT</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Process CPU-Time Clocks <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the CPT margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the CPT margin legend.</p>

<p><sup>[<a href="javascript:open_code('CS')">CS</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Clock Selection <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the CS margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the CS margin legend.</p>

<p><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Extension to the ISO&nbsp;C standard <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is an extension to the ISO&nbsp;C standard. Application writers may make use of an extension as it is
supported on all IEEE&nbsp;Std&nbsp;1003.1-2001-conforming systems.</p>

<p>With each function or header from the ISO&nbsp;C standard, a statement to the effect that &quot;any conflict is unintentional&quot; is
included. That is intended to refer to a direct conflict. IEEE&nbsp;Std&nbsp;1003.1-2001 acts in part as a profile of the
ISO&nbsp;C standard, and it may choose to further constrain behaviors allowed to vary by the ISO&nbsp;C standard. Such limitations
are not considered conflicts.</p>

<p>Where additional semantics apply to a function or header, the material is identified by use of the CX margin legend.</p>

<p><sup>[<a href="javascript:open_code('FD')">FD</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
FORTRAN Development Utilities <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional.</p>

<p>Where applicable, utilities are marked with the FD margin legend in the SYNOPSIS section. Where additional semantics apply to a
utility, the material is identified by use of the FD margin legend.</p>

<p><sup>[<a href="javascript:open_code('FR')">FR</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
FORTRAN Runtime Utilities <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional.</p>

<p>Where applicable, utilities are marked with the FR margin legend in the SYNOPSIS section. Where additional semantics apply to a
utility, the material is identified by use of the FR margin legend.</p>

<p><sup>[<a href="javascript:open_code('FSC')">FSC</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
File Synchronization <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the FSC margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the FSC margin legend.</p>

<p><sup>[<a href="javascript:open_code('IP6')">IP6</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
IPV6 <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the IP6 margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the IP6 margin legend.</p>

<p><sup>[<a href="javascript:open_code('MC1')">MC1</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Advisory Information and either Memory Mapped Files or Shared Memory Objects <img src="../images/opt-end.gif" alt="[Option End]"
border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>This is a shorthand notation for combinations of multiple option codes.</p>

<p>Where applicable, functions are marked with the MC1 margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the MC1 margin legend.</p>

<p>Refer to the Base Definitions volume of IEEE&nbsp;Std&nbsp;1003.1-2001, <a href=
"../basedefs/xbd_chap01.html#tag_01_05_02">Section 1.5.2, Margin Code Notation</a>.</p>

<p><sup>[<a href="javascript:open_code('MC2')">MC2</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Memory Mapped Files, Shared Memory Objects, or Memory Protection <img src="../images/opt-end.gif" alt="[Option End]" border=
"0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>This is a shorthand notation for combinations of multiple option codes.</p>

<p>Where applicable, functions are marked with the MC2 margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the MC2 margin legend.</p>

<p>Refer to the Base Definitions volume of IEEE&nbsp;Std&nbsp;1003.1-2001, <a href=
"../basedefs/xbd_chap01.html#tag_01_05_02">Section 1.5.2, Margin Code Notation</a>.</p>

<p><sup>[<a href="javascript:open_code('MC3')">MC3</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Memory Mapped Files, Shared Memory Objects, or Typed Memory Objects <img src="../images/opt-end.gif" alt="[Option End]" border=
"0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>This is a shorthand notation for combinations of multiple option codes.</p>

<p>Where applicable, functions are marked with the MC3 margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the MC3 margin legend.</p>

<p>Refer to the Base Definitions volume of IEEE&nbsp;Std&nbsp;1003.1-2001, <a href=
"../basedefs/xbd_chap01.html#tag_01_05_02">Section 1.5.2, Margin Code Notation</a>.</p>

<p><sup>[<a href="javascript:open_code('MF')">MF</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Memory Mapped Files <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the MF margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the MF margin legend.</p>

<p><sup>[<a href="javascript:open_code('ML')">ML</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Process Memory Locking <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the ML margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the ML margin legend.</p>

<p><sup>[<a href="javascript:open_code('MR')">MR</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Range Memory Locking <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the MLR margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the MLR margin legend.</p>

<p><sup>[<a href="javascript:open_code('MON')">MON</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Monotonic Clock <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the MON margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the MON margin legend.</p>

<p><sup>[<a href="javascript:open_code('MPR')">MPR</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Memory Protection <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the MPR margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the MPR margin legend.</p>

<p><sup>[<a href="javascript:open_code('MSG')">MSG</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Message Passing <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the MSG margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the MSG margin legend.</p>

<p><sup>[<a href="javascript:open_code('MX')">MX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> IEC
60559 Floating-Point Option <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the MX margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the MX margin legend.</p>

<p><sup>[<a href="javascript:open_code('OB')">OB</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Obsolescent <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described may be withdrawn in a future version of this volume of IEEE&nbsp;Std&nbsp;1003.1-2001. Strictly
Conforming POSIX Applications and Strictly Conforming XSI Applications shall not use obsolescent features.</p>

<p>Where applicable, the material is identified by use of the OB margin legend.</p>

<p><sup>[<a href="javascript:open_code('OF')">OF</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Output Format Incompletely Specified <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is an XSI extension. The format of the output produced by the utility is not fully specified. It is
therefore not possible to post-process this output in a consistent fashion. Typical problems include unknown length of strings and
unspecified field delimiters.</p>

<p>Where applicable, the material is identified by use of the OF margin legend.</p>

<p><sup>[<a href="javascript:open_code('OH')">OH</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Optional Header <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 In the SYNOPSIS section of some interfaces in the System Interfaces volume of IEEE&nbsp;Std&nbsp;1003.1-2001 an included header is
marked as in the following example:</p>

<pre>
<tt><sup>[<a href="javascript:open_code('OH')">OH</a>]</sup><img src="../images/opt-start.gif" alt="[Option Start]" border="0">
#include &lt;sys/types.h&gt;
<img src="../images/opt-end.gif" alt="[Option End]" border="0">
#include &lt;grp.h&gt;
struct group *getgrnam(const char *name);
</tt>
</pre>

<p>The OH margin legend indicates that the marked header is not required on XSI-conformant systems.</p>

<p><sup>[<a href="javascript:open_code('PIO')">PIO</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Prioritized Input and Output <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the PIO margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the PIO margin legend.</p>

<p><sup>[<a href="javascript:open_code('PS')">PS</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Process Scheduling <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the PS margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the PS margin legend.</p>

<p><sup>[<a href="javascript:open_code('RS')">RS</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0"> Raw
Sockets <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the RS margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the RS margin legend.</p>

<p><sup>[<a href="javascript:open_code('RTS')">RTS</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Realtime Signals Extension <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the RTS margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the RTS margin legend.</p>

<p><sup>[<a href="javascript:open_code('SD')">SD</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Software Development Utilities <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional.</p>

<p>Where applicable, utilities are marked with the SD margin legend in the SYNOPSIS section. Where additional semantics apply to a
utility, the material is identified by use of the SD margin legend.</p>

<p><sup>[<a href="javascript:open_code('SEM')">SEM</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Semaphores <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the SEM margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the SEM margin legend.</p>

<p><sup>[<a href="javascript:open_code('SHM')">SHM</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Shared Memory Objects <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the SHM margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the SHM margin legend.</p>

<p><sup>[<a href="javascript:open_code('SIO')">SIO</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Synchronized Input and Output <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the SIO margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the SIO margin legend.</p>

<p><sup>[<a href="javascript:open_code('SPI')">SPI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Spin Locks <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the SPI margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the SPI margin legend.</p>

<p><sup>[<a href="javascript:open_code('SPN')">SPN</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Spawn <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the SPN margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the SPN margin legend.</p>

<p><sup>[<a href="javascript:open_code('SS')">SS</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Process Sporadic Server <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the SS margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the SS margin legend.</p>

<p><sup>[<a href="javascript:open_code('TCT')">TCT</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Thread CPU-Time Clocks <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the TCT margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the TCT margin legend.</p>

<p><sup>[<a href="javascript:open_code('TEF')">TEF</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Trace Event Filter <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the TEF margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the TEF margin legend.</p>

<p><sup>[<a href="javascript:open_code('THR')">THR</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Threads <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the THR margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the THR margin legend.</p>

<p><sup>[<a href="javascript:open_code('TMO')">TMO</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Timeouts <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the TMO margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the TMO margin legend.</p>

<p><sup>[<a href="javascript:open_code('TMR')">TMR</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Timers <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the TMR margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the TMR margin legend.</p>

<p><sup>[<a href="javascript:open_code('TPI')">TPI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Thread Priority Inheritance <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the TPI margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the TPI margin legend.</p>

<p><sup>[<a href="javascript:open_code('TPP')">TPP</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Thread Priority Protection <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the TPP margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the TPP margin legend.</p>

<p><sup>[<a href="javascript:open_code('TPS')">TPS</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Thread Execution Scheduling <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the TPS margin legend for the SYNOPSIS section. Where additional semantics apply to
a function, the material is identified by use of the TPS margin legend.</p>

<p><sup>[<a href="javascript:open_code('TRC')">TRC</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Trace <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the TRC margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the TRC margin legend.</p>

<p><sup>[<a href="javascript:open_code('TRI')">TRI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Trace Inherit <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The functionality described is optional. The functionality described is also an extension to the ISO&nbsp;C standard.</p>

<p>Where applicable, functions are marked with the TRI margin legend in the SYNOPSIS section. Where additional semantics apply to a
function, the material is identified by use of the TRI margin legend.</p>

<p><sup>[<a href="javascript:open_code('TRL')">TRL</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Trace Log <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
 The