Meaning of "handle" when using tc filter ... flow hash

Hi,

I've been using the "flow hash keys" feature of tc to evenly distribute
bandwidth across client IP addresses.

In order to get it to work, I have to specify a "handle" value:

$TC filter add dev eth0 parent 4101: protocol ip \
	handle 10 flow hash keys dst divisor 1024

         ^^^^

However, the handle doesn't seem to do anything. No matter what value I
specify, the rule works. If I leave it out, I get an "RTNETLINK answers:
Invalid argument" error.

I would normally expect the handle parameter to specify a netfilter mark
value. In this case though, it doesn't seem to make any difference. Is
there a reason that it needs to be specified?

Thanks,

Andy