throws ReportException {
MathExpression express = null;
String tag = element.getName();
if(tag.equals(MathExpressionSubReportColumnRef.TAG)) {
express = new MathExpressionSubReportColumnRef(element,
cf.getChildContext(MathExpressionSubReportColumnRef.GROUP));
} else if(tag.equals(MathExpressionOperatorRef.TAG)) {
express = new MathExpressionOperatorRef(element,
cf.getChildContext(MathExpressionOperatorRef.GROUP));