function readurl() {
	var url = window.location.href;
	var pos = url.indexOf('p='); //pageinfo
	if (pos != -1) {
		divp = url.substring(pos + 2, pos + 3);
	}
	var pos = url.indexOf('h='); //headerinfo
	if (pos != -1) {
		divh = url.substring(pos + 2, pos + 3);
	}
	var pos = url.indexOf('s='); //subjectinfo
	if (pos != -1) {
		divs = url.substring(pos + 2, pos + 3);
	}
}	
function setpage(divp, divh, divs, mode) {
	var e = null;
	if (mode == '') {
		document.getElementById("tab1").style.backgroundImage = 
		 'url(images/foto' + divp.toString() + '_' + divh.toString() + '.jpg)';
		document.getElementById('imgM' + divp).src = document.getElementById('imgM' + divp).src.replace('.gif', '_on.gif');
	}
	else {
		document.getElementById('imgM' + divp).src = document.getElementById('imgM' + divp).src.replace('_on.gif', '.gif');
	}
	document.getElementById('divp' + divp).style.display = mode;
	document.getElementById('divh' + divp + '_' + divh).style.display = mode;
	document.getElementById('divs' + divp + '_' + divh + '_' + divs).style.display = mode;
}
function nextpage(i) {
	if (i!=0) {
		document.getElementById('divs' + divp + '_' + divh + '_' + divs).style.display = 'none';
		divs = parseInt(divs) + i;
		el = document.getElementById('divs' + divp + '_' + divh + '_' + divs)
		if (el) {
			el.style.display = '';
		}
		else {
			divs = parseInt(divs) - i;
			el.style.display = '';
		}
	}
	if (divs<=1) {
		document.getElementById('prevpage').style.visibility = 'hidden';
	}
	else {
		document.getElementById('prevpage').style.visibility = '';
	}
	if (document.getElementById('divs' + divp + '_' + divh + '_' + (parseInt(divs) + 1))) {
		document.getElementById('nextpage').style.visibility = '';
	}
	else {
		document.getElementById('nextpage').style.visibility = 'hidden';
	}
	if (document.getElementById('nextpage').style.visibility == '' && document.getElementById('prevpage').style.visibility == '') {
		document.getElementById('pagesep').style.visibility = '';
	}
	else {
		document.getElementById('pagesep').style.visibility = 'hidden';
	}
}
function gotopage(p, h, s) {
	setpage(divp, divh, divs, 'none');
	setpage(p, h, s, '')
	divp = p;
	divh = h;
	divs = s;
	nextpage(0);
}
function navigatie_ov(e) {
	linkEl = (NS4) ? e.target : (FF) ? e.currentTarget : event.srcElement;
	linkEl.src = linkEl.src.replace('.jpg','_ov.jpg');
}function navigatie_out(e) {
	linkEl = (NS4) ? e.target : (FF) ? e.currentTarget : event.srcElement;
	linkEl.src = linkEl.src.replace('_ov.jpg','.jpg');
}