xit/2</span></a>
and <a class="reference internal" href="threaded_cancel_1.html#predicates-threaded-cancel-1"><span class="std std-ref">threaded_cancel/1</span></a> predicates. Tags shall be regarded
as opaque terms; users shall not rely on their type.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>This predicate requires a <a class="reference internal" href="../../glossary.html#term-backend-Prolog-compiler"><span class="xref std std-term">backend Prolog compiler</span></a> provid