function dateAdd( start, interval, number ) {
	
    // Create 3 error messages, 1 for each argument. 
    var startMsg = "Sorry the start parameter of the dateAdd function\n"
        startMsg += "must be a valid date format.\n\n"
        startMsg += "Please try again." ;
		
    var intervalMsg = "Sorry the dateAdd function only accepts\n"
        intervalMsg += "d, h, m OR s intervals.\n\n"
        intervalMsg += "Please try again." ;

    var numberMsg = "Sorry the number parameter of the dateAdd function\n"
        numberMsg += "must be numeric.\n\n"
        numberMsg += "Please try again." ;
		
    // get the milliseconds for this Date object. 
    var buffer = Date.parse( start ) ;
	
    // check that the start parameter is a valid Date. 
    if ( isNaN (buffer) ) {
        alert( startMsg ) ;
        return null ;
    }
	
    // check that an interval parameter was not numeric. 
    if ( interval.charAt == 'undefined' ) {
        // the user specified an incorrect interval, handle the error. 
        alert( intervalMsg ) ;
        return null ;
    }

    // check that the number parameter is numeric. 
    if ( isNaN ( number ) )	{
        alert( numberMsg ) ;
        return null ;
    }

    // so far, so good...
    //
    // what kind of add to do? 
    switch (interval.charAt(0))
    {
        case 'd': case 'D': 
            number *= 24 ; // days to hours
            // fall through! 
        case 'h': case 'H':
            number *= 60 ; // hours to minutes
            // fall through! 
        case 'm': case 'M':
            number *= 60 ; // minutes to seconds
            // fall through! 
        case 's': case 'S':
            number *= 1000 ; // seconds to milliseconds
            break ;
        default:
        // If we get to here then the interval parameter
        // didn't meet the d,h,m,s criteria.  Handle
        // the error. 		
        alert(intervalMsg) ;
        return null ;
    }
    return new Date(buffer - number) ;
}
 function TwoDigitDate(sVal)
 {
	var objStr			= new String(sVal);
	var intStringLen	= objStr.length;
	var strVal="";
	if (intStringLen == 1)
	{
		switch (intStringLen)
		{
			case 1:
				strVal	= "0"+sVal;
			break;
		}	
	}
	else
	{
		strVal = sVal;
	}
	return strVal;
 }


function suycDateDiff( start, end, interval, rounding ) 
{

    var iOut = 0;
    var bufferA = Date.parse( start ) ;
    var bufferB = Date.parse( end ) ;
    // check that an interval parameter was not numeric. 
    var intervalMsg="";
    var number = bufferB-bufferA ;
    
    // what kind of add to do? 
    switch (interval.charAt(0))
    {
        case 'd': case 'D': 
            iOut = parseInt(number / 86400000) ;
            if(rounding) iOut += parseInt((number % 86400000)/43200001) ;
            break ;
        case 'h': case 'H':
            iOut = parseInt(number / 3600000 ) ;
            if(rounding) iOut += parseInt((number % 3600000)/1800001) ;
            break ;
        case 'm': case 'M':
            iOut = parseInt(number / 60000 ) ;
            if(rounding) iOut += parseInt((number % 60000)/30001) ;
            break ;
        case 's': case 'S':
            iOut = parseInt(number / 1000 ) ;
            if(rounding) iOut += parseInt((number % 1000)/501) ;
            break ;
        default:
        // If we get to here then the interval parameter
        // didn't meet the d,h,m,s criteria.  Handle
        // the error. 		
        alert(intervalMsg) ;
        return null ;
    }
    
    return iOut ;
}


// The presentDate function is called on when you 
// click on the button on the form.
function presentDate() 
{
    var roundDays = 1;
    var objDate = new Date();
    var strToday = (objDate.getMonth()+1)+"/"+ objDate.getDate()+"/"+objDate.getYear()
    
    var e = new Date(Date.parse(strNewDate)) ;
    var s = new Date(Date.parse(strToday)) ;
    var temp = suycDateDiff( s, e,'D',1);
    document.frmBookTreatment.hidDate.value=temp
}