ntics for the transcendental functions has been
specified more fully.
</p>
<li><p>The semantics of <tt>expt</tt> for zero bases has been refined.
</p>
<li><p>In <tt>syntax-rules</tt> forms, a <tt>_</tt> may be used in place of
the keyword.
</p>
<li><p>The <tt>let-syntax</tt> and <tt>letrec-syntax</tt> no longer introduce a
new environment for their bodies.
</p>
<li><p>For implementations that support NaNs or infinities,
many arithmetic operations have been specified on
these values consistently with IEEE&nb