function showBlock(myTable, trIdPrefix) {
	//zobrazi alebo schova riadky tabulky na zaklade preddefinovaneho preficu id tr elementu

	var tableObject = document.getElementById(myTable);
	var tBodyObject = tableObject.getElementsByTagName("TBODY").item(0);

	for(var i = 0; i < tBodyObject.getElementsByTagName("TR").length; i++) {
		var trObject = tBodyObject.getElementsByTagName("TR").item(i);
		if(trObject.id.indexOf(trIdPrefix) > -1) {
			if(trObject.style.display == 'none') {
				trObject.style.display = 'block';
			} else {
				trObject.style.display = 'none';
			}
		}
	}
}