function validate_quantity(form) 
{
	if (form.quantity.value == "" || form.quantity.value == "0")
	{ 
	   alert("Please Enter a number for quantity."); 
	   form.quantity.focus( ); 
	   return false;
	}
	else if (isNaN(form.quantity.value))
	{
	   alert("Please Enter a number for quantity."); 
	   form.quantity.focus( ); 
	   return false;		
	}
  	else if (form.quantity.value > 999)
	{
	   alert("Quantity must be less than or equal to 999."); 
	   form.quantity.focus( ); 
	   return false;		
	}							
}//validate_quantity