Passthrough Frsky Telemetry

I know this isn’t specific to 3.5 but not sure where else to post it. In the Copter guide here:
Mention is made of a specification as follows, “The ArduPilot passthrough telemetry specification including data packets and message rates is available as a spreadsheet” but the link to this is broken. I would like to understand how to use this. I’m currently using Frsky telemetry via thge “repurposed” method and it works fine but it looks like Passthrough to Open TX supports more metrics.