="623,128 620,122 614,116 604,112 592,109 578,108 564,109 551,112 541,116 535,122 533,128 535,134 541,140 551,144 564,147 578,148 592,147 604,144 614,140 620,134"/>
		</map>
	<h2>Classes, Fields and Messages</h2>
	<p>Classes have both <i>fields</i> and <i>messages.</i> Messages are either <i>implicit</i> or <i>explicit</i> where an implicit message is one of:</p>
	<ul>
	<li> a constructor (usually called &quot;create&quot;);</li>
	<li> a destructor (usually called &quot;destroy&quot;);</li>
	<li> &quot;get_