>
    <LI>evaluate the resulting boolean value</LI>
    <LI>ignore the element contents if the value is 'false'</LI>
    <LI>otherwise execute the element contents</LI>
  </UL>

  <P>There is onle type of function call that makes this a bit more complicated.
  The <CODE><FONT face="courier, monospaced">function-available()</FONT></CODE> and <CODE><FONT face="courier, monospaced">element-available()</FONT></CODE>
  function calls can be used to test for extension elements and functions. A
  very common use f