Local Metrics are metrics that are scoped to an individual experiment. They let you create a custom metric you want to measure in the context of your experiment or gate, without having to clutter up your Metrics Catalog with these metrics. Local Metrics can be created from the Setup tab sections of your experiment. They will be calculated for the duration of your experiment or rollout, and then will cease to exist when you make a decision on your experiment.
Our April release allowed you to create simple metrics (sums, count, unique user count). By popular demand, we've unlocked all the flexibility available in the metrics catalog - windowing, SQL filters and metrics that span multiple metric sources.