function SD_reveal (idtag) {
	var element = document.getElementById(idtag);
	var clicker = document.getElementById(idtag+'-ctrl');
	if(element.style.display == 'none') {
		element.style.display = 'block';
		clicker.innerHTML = 'Close <<';
	} else {
		element.style.display = 'none';
		clicker.innerHTML = 'Read more >>';
	}
}