  <span class="keywordtype">integer</span> :: low</div>
<div class="line"><a name="l00055"></a><span class="lineno">   55</span>&#160;  <span class="keywordtype">integer</span> :: high</div>
<div class="line"><a name="l00056"></a><span class="lineno">   56</span>&#160;  <span class="keywordtype">integer</span> :: lower(stack_levels)</div>
<div class="line"><a name="l00057"></a><span class="lineno">   57</span>&#160;  <span class="keywordtype">integer</span> :: upper(stack_levels)</div>
<div class="line"><a 