function chk_email(obj, len)
	{
	chk_txt(obj, len);
	var check = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-]{2,})+\.)+([a-zA-Z0-9]{2,})+$/;        
    if (obj.value.search(check) && obj.value != '')		
		return false;
	else
		return true;		
	}

function chk_txt(obj, len)
	{
	digited = obj.value.length;
	if (digited > len)
		return false;
	else
		return true;
	}
	
function chk_numeric (obj, len) 
		{
		boolReturn=false;
		if (chk_txt (obj, len))
			{
			chk_txt(obj, len);	
			var str_num = obj.value;		
			if (str_num != '')
				{			
				var codreg = /^([0-9]{1,})+$/;
				if (codreg.test(str_num))					
					boolReturn=true;
					
				}
			}
		return boolReturn;
		}

function chk_alfanum (obj, len) {
		boolReturn=false;
		if (chk_txt(obj, len))
			{
			var str_alfa = obj.value;		
			if (str_alfa != '')
				{			
				var codreg = /^([0-9a-zA-Z]{1,})+$/;
				if (!codreg.test(str_alfa))
					{
					boolReturn=true;
					}
				}
			}
		return boolReturn;
		}