help with mangle

Hi,
There is a situation,i need to mangle an external traffic(count it and exclude local traffic of ISP) and internal traffic of ISP. I found the sample in manual :

/ip firewall mangle
add in-interface=ether1 dst-address=159.148.0.0/16 action=passthrough
.. mark-connection=mark-con-latvia comment=“mark all latvian traffic”
add dst-address=193.41.195.0/24 action=passthrough
.. mark-connection=mark-con-latvia comment=“mark all latvian traffic”
add dst-address=193.41.33.0/24 action=passthrough
.. mark-connection=mark-con-latvia comment=“mark all latvian traffic”
add dst-address=193.41.45.0/24 action=passthrough
.. mark-connection=mark-con-latvia comment=“mark all latvian traffic”
add dst-address=193.68.64.0/19 action=passthrough
.. mark-connection=mark-con-latvia comment=“mark all latvian traffic”

add connection=mark-con-latvia action=passthrough mark-flow=latvia comment=“mark latvia”
add flow=!latvia action=passthrough mark-flow=overseas comment=“mark all oversea traffic”

QUESTION: Why there was used “dst-address” ? If i want to shape the download traffic , what address i have to use DST or SRC ? ? ? ?

I mean

—WAN(internal external traffic)—>(MT)—>mee
—DOWNLOADING----------------------------->mee
src---->(MT)----->dst (mee)

add dst-address=193.41.195.0/24 action=passthrough
mark-connection=mark-con-latvia comment=“mark all latvian traffic”

maybe src-address=193.41.195.0/24 ? ? ? ? ? ? ? ?