tc-ematch(8) extended matches for use with "basic", "cgroup" or "flow" filters
man7.orgSpare some context for a poor old blind beggar?
tc is Traffic Control for Linux, you can do things like set priorities, drop traffic for testing, etc. This looks like now you could match by systemd service, container, or some other thing with its own group, which sounds useful.
I don't know, this feature looks old though, not sure why it's here.