Metrics query endpoint fields

Using the metrics query endpoint: https://a.klaviyo.com/api/v1/metric/metric_id/export I have been successful pulling metrics using both the “by” and “where” query parameters. This tool is greatly appreciated.

I am having a hard time finding the corresponding fields for the “where” and “by” parameters with arguments like `by = $message`. It can take some guesswork to match an analytics UI field with what the queries pull from in your back end. Is there a table or list of Klaviyo fields I can pull from? The specific field I’m looking for is the a/b test ID, but there are quite a few times I’ve run into not being able to guess the proper field name.