//
		//
		ExpressionOperator toTime = new ExpressionOperator();
		toTime.addSelector("toTime");
		Vector t = new Vector();
		t.addElement("TO_CHAR(");
		t.addElement(", 'YYYYMMDDHH24MI')");
		toTime.printsAs(t);
		toTime.bePrefix();
		toTime.setNodeClass(TOPLink.Private.Expressions.FunctionExpression.class);
		ExpressionOperator.initializeOperators();
		ExpressionOperator.addOperator(toTime);

Expression expr = toTime.expressionFor(exp.get("fieldMeetdatum"));