@Override
	protected  
	AbstractPage parseChild(Element element) throws ProblemsReadingDocumentException {
		try {
			trackCounter++; // that includes counting for failed parsing
			URL u = resolveLink(element.getAttributeValue("href"));
			Track t;
			t = new Track(u.toString(), getChildrenSaveTo(), this);
			t.setTitle(element.getValue());
			// may be set default property instead?
			t.setProperty("track", String.valueOf(trackCounter));
			return t;
		} catch (IllegalArgumentException|NullPointerException|
				IOException e) {
			throw new ProblemsReadingDocumentException(e);
		}
	}