MEDIAN: IndicatorDescriptor = ...

Median — the nearest-rank 50th percentile of the source, banded by ATR and shaded against its own EMA. The percentile is a real member of the window rather than an interpolation (see percentileNearestRank), so on an even-length window it is the upper of the two middles, not their mean.

The EMA is chained onto the percentile series, so it inherits that series' warmup and first prints at 2 * length - 2 — see emaOfGapped.