At home, I have my own network. I have set up a DHCP fixed-address connection for that.
However, not all networks like that, and so I have set up another Service in Network preferences that just uses plain DHCP.
However, I can't set them to only connect to certain networks: changing settings in the Advanced window adjusts them for all Wi-Fi Services. This means I have both connections going.
How do I change the settings for just one Service, so I can set it to only connect to a certain network?