var arrMonths = new Array("January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December");

var intYear;
var intMonth;
var strEstablishment;
var strYearFieldName;
var strMonthFieldName;

function PreviousMonth()
{
    intMonth--;
    if(intMonth == 0)
    {
        intMonth = 12;
        intYear--;
    }
    
    ShowMonth(intMonth, arrMonths[intMonth - 1], intYear);
}

function NextMonth()
{
    intMonth++;
    if(intMonth == 13)
    {
        intMonth = 1;
        intYear++;
    }

    ShowMonth(intMonth, arrMonths[intMonth - 1], intYear);
}

function ShowMonth(Month, MonthName, Year)
{
    objMonthField = document.getElementById(strMonthFieldName);
    if(objMonthField)
        objMonthField.innerHTML = MonthName;

    objYearField = document.getElementById(strYearFieldName);
    if(objYearField)
        objYearField.innerHTML = Year;

    objFrame = document.getElementById('frmCalendar');
    if(objFrame)
        objFrame.src = 'rates_cal.aspx?name=' + strEstablishment + '&year=' + intYear + '&month=' + intMonth;
}