Complete list of fields supported by load balancing rules

Hello! I want to split my traffic across multiple backends by geographical location of the client. I see that it is load balancing feature. But geo steering by Cloudflare region or datacenter is inaccurate for me.

I see that load balancer has custom rules feature, and it’s supports some set of fields for rules. https://developers.cloudflare.com/load-balancing/additional-options/load-balancing-rules/reference

According to the doc, IP address, Load Balancer Region and Load Balancer Name are supported. On screenshot from doc I see that Request Method, Request URI, Timestamp, Header (which header?) are probably supported. But I’m not sure

For the most up to date list of these fields, create a load balancing rule in the UI.

I can’t create load balancing rule because load balancing is not enabled for my account. But I want to know which fields are supported, and especially can I use CF-IPCountry header value in load balancing rules, or this header is not present in the traffic on the rules processing step, before the load balancing activation. Enterprise account, geolocation is on.

Please share you knowledge. Maybe I am on the wrong way.