function justNumbers(e,o)
{
	var key;
	var keychar;
	
	if (window.event) 
		key = window.event.keyCode;
	else if (e) 
		key = e.which;
	else 
		return true;
	
	keychar = String.fromCharCode(key);
	keychar = keychar.toLowerCase();
	
	// control keys
	if ((key==null) || (key==0) || (key==8) ||  (key==9) || (key==13) || (key==27) ) 
		return true;
	// alphas and numbers que se permiten
	else 
	{
		if(o.value.indexOf('.')==-1)
		{
			if ((("01234567893.").indexOf(keychar) > -1)) 	
				return true;	
			else 		
				return false;
		} 
		else 
		{
			if ((("01234567893").indexOf(keychar) > -1)) 	
				return true;	
			else 		
				return false;
		}
	}
}