title: Jasper report syntax reportelement and frame
body: <p>I'm trying to understand how jasper reports work but i find the syntax a little difficult to get to grips with.</p>
  
  <p>what exactly does reportelement- key refer to? also is frame a purely visual component?</p>
  
  
  
  <pre><code>&lt;frame&gt;
      &lt;reportElement key="frame-6" mode="Opaque" x="0" y="36" width="534" height="36" backcolor="#CCCCCC"/&gt;
      &lt;box&gt;
          &lt;topPen lineWidth="0.0" lineStyle="Solid" lineColor="#000000"/&gt;
          &lt;leftPen lineWidth="0.0" lineStyle="Solid" lineColor="#000000"/&gt;
          &lt;bottomPen lineWidth="0.0" lineColor="#000000"/&gt;
          &lt;rightPen lineWidth="0.0" lineStyle="Solid" lineColor="#000000"/&gt;
      &lt;/box&gt;
  &lt;/frame&gt;
  </code></pre>
  
  <p>Also in the following what do the F and v indicate, and more importantly where are they defined?</p>
  
  
  
  <pre><code>&lt;textFieldExpression class="java.math.BigDecimal"&gt;&lt;![CDATA[$V{amountTotal}]]&gt;&lt;/textFieldExpression&gt;
  &lt;variableExpression&gt;&lt;![CDATA[new BigDecimal($F{amount percentage})&lt;/variableExpression&gt;
  </code></pre>