public MathExpressionEntityFieldRef(Element element, Context context) throws ReportException {
super(element, context);
String fullname = getStringAttribute(element, ATTR_VALUE);
int aliaspos = fullname.indexOf('.');
Atom atom = new Atom(fullname.substring(0, aliaspos));
QEntity entity = context.getEntity(atom);
String propertyName = fullname.substring(aliaspos+1);
ContextGroup contextGroup = getContextGroup(entity.getContextGroup());
property = context.getProperty(contextGroup, entity, propertyName);