function hideBlock(nr)
    {
    	if (document.layers)
    	{
    		current = document.layers[nr].display;
            if (current == 'block') document.layers[nr].display = 'none';
    	}
    	else if (document.all)
    	{
    		current = document.all[nr].style.display;
            if (current == 'block') document.all[nr].style.display = 'none';
    	}
    	else if (document.getElementById)
    	{
    		vista = document.getElementById(nr).style.display;
            if (vista == 'block') document.getElementById(nr).style.display = 'none';
    	}
    }
    function showBlock(nr)
    {
    	if (document.layers)
    	{
    		current = document.layers[nr].display;
            if (current == 'none') document.layers[nr].display = 'block';
    	}
    	else if (document.all)
    	{
    		current = document.all[nr].style.display;
            if (current == 'none') document.all[nr].style.display = 'block';
    	}
    	else if (document.getElementById)
    	{
    		vista = document.getElementById(nr).style.display;
            if (vista == 'none') document.getElementById(nr).style.display = 'block';
    	}
    }


    function switchVisibility (obj) {

        idx = document.register.elements["form_uni"].selectedIndex
        val = document.register.elements["form_uni"].options[idx].value
        if (val == "Sonstige Ausland" || val == "Sonstige Uni") {
            showBlock (obj);
        } else hideBlock (obj);

    }

    // wenn seite neu geladen wird, feststellen, ob feld unsichtbar sein muss oder nicht
 //    switchVisibility('sonstige');