Tunnel 2.0 PAC file variable

Hi, can someone tell me what this variable is for PAC file configurations for Tunnel 2.0?
${ZAPP_TUNNEL2_BYPASS}

https://help.zscaler.com/z-app/best-practices-adding-bypasses-z-tunnel-2.0?_ga=2.179416612.1241781466.1584938403-1177754173.1579504917

It is written in this URL, and I was curious where I can declare the variable.
I wanted to declare this variable to an IP address for our on premise proxy server.