function DocDataValues(year_param, month_param, day_param) {
	this.dd = Number(document.short_nav.dd.value) + day_param;
	this.mm = Number(document.short_nav.mm.value) - 1 + month_param;
	this.yyyy = Number(document.short_nav.yyyy.value) + year_param;
	if ((this.dd == 0) && (this.mm == 0)) {
		// avoid NS 4 "bug" / behaviour / feature
		this.dd = 31;
		this.mm = 11;
		this.yyyy--;
	}
	ddate = new Date(this.yyyy, this.mm, this.dd);
	this.dd = ddate.getDate();
	this.mm = ddate.getMonth() + 1;
	this.yyyy = ddate.getYear();
	if (this.yyyy < 200) this.yyyy += 1900;  // yet another NS 4 special... 
	if (this.dd < 10) this.dd = "0" + this.dd;
}

function WriteDateInDocument(curDateValues) {
	if (document.getElementById) {
		if (document.short_nav.dd.value != curDateValues.dd) 
			document.getElementById("day").innerHTML = curDateValues.dd;
		if (document.short_nav.mm.value != curDateValues.mm) 
			document.getElementById("month").innerHTML = monthsList[curDateValues.mm];
		if (document.short_nav.yyyy.value != curDateValues.yyyy) 
			document.getElementById("year").innerHTML = curDateValues.yyyy;
	} else 	if (document.all) {
		if (document.short_nav.dd.value != curDateValues.dd) 
			document.all.day.innerText = curDateValues.dd;
		if (document.short_nav.mm.value != curDateValues.mm) 
			document.all.month.innerText = monthsList[curDateValues.mm];
		if (document.short_nav.yyyy.value != curDateValues.yyyy) 
			document.all.year.innerText = curDateValues.yyyy;
	} else {
		if (document.short_nav.dd.value != curDateValues.dd) {
			document.nsiday.document.nsday.document.write("<span class=\"short-nav\">" + curDateValues.dd + "</span>");
			document.nsiday.document.nsday.document.close()
		}
		if (document.short_nav.mm.value != curDateValues.mm) {
			document.nsimonth.document.nsmonth.document.write("<span class=\"short-nav\">" + monthsList[curDateValues.mm] + "</span>");
			document.nsimonth.document.nsmonth.document.close()
		}
		if (document.short_nav.yyyy.value != curDateValues.yyyy) {
			document.nsiyear.document.nsyear.document.write("<span class=\"short-nav\">" + curDateValues.yyyy + "</span>");
			document.nsiyear.document.nsyear.document.close()
		}
	}
	document.short_nav.dd.value = curDateValues.dd;
	document.short_nav.mm.value = curDateValues.mm;
	document.short_nav.yyyy.value = curDateValues.yyyy;
}

function minus_day() { 
	WriteDateInDocument(new DocDataValues(0, 0, -1));
}

function plus_day() { 
	WriteDateInDocument(new DocDataValues(0, 0, +1));
}	

function minus_month() { 
	WriteDateInDocument(new DocDataValues(0, -1, 0));
}

function plus_month() { 
	WriteDateInDocument(new DocDataValues(0, +1, 0));
}

function minus_year() { 
	WriteDateInDocument(new DocDataValues(-1, 0, 0));
}

function plus_year() { 
	WriteDateInDocument(new DocDataValues(+1, 0, 0));
}