<function>glWaitSync</function> causes the GL server to block and wait until <parameter>sync</parameter> becomes signaled. <parameter>sync</parameter>
is the name of an existing sync object upon which to wait. <parameter>flags</parameter> and <parameter>timeout</parameter> are currently not used and
must be set to zero and the special value <constant>GL_TIMEOUT_IGNORED</constant>, respectively<footnote><para><parameter>flags</parameter> and
<parameter>timeout</parameter> are placeholders for anticipated future extensions of sync object capabilities. They must have these reserved values in
order that existing code calling <function>glWaitSync</function> operate properly in the presence of such extensions.</para></footnote>. <function>glWaitSync</function> will always wait no longer than an implementation-dependent timeout. The
duration of this timeout in nanoseconds may be queried by calling <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with the
parameter <constant>GL_MAX_SERVER_WAIT_TIMEOUT</constant>. There is currently no way to determine whether <function>glWaitSync</function> unblocked
because the timeout expired or because the sync object being waited on was signaled.
</para>
<para>
If an error occurs, <function>glWaitSync</function> does not cause the GL server to block.
</para>
</refsect1>
<refsect1id="notes"><title>Notes</title>
<para>
<function>glWaitSync</function> is available only if the GL version is 3.2 or higher.
</para>
</refsect1>
<refsect1id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_OPERATION</constant> is generated if <parameter>sync</parameter> is not the name of a sync object.
</para>
<para>
<constant>GL_INVALID_VALUE</constant> is generated if <parameter>flags</parameter> is not zero.
</para>
<para>
<constant>GL_INVALID_VALUE</constant> is generated if <parameter>timeout</parameter> is not <constant>GL_TIMEOUT_IGNORED</constant>.