public Event execute(final XMLConsumer consumer,
ExpressionContext expressionContext, ExecutionContext executionContext,
MacroContext macroContext, Event startEvent, Event endEvent)
throws SAXException {
String uri;
AttributeEvent e = this.uri;
if (e instanceof CopyAttribute) {
CopyAttribute copy = (CopyAttribute) e;
uri = copy.getValue();
} else {
StringBuffer buf = new StringBuffer();