The category this boxen summarises.
The middle of the distribution.
The rungs, which the trace sorts outward from the median rather than trusting the order they arrive in -- a producer emitting them inward-first would otherwise be navigated backwards.
OptionallowerValues beyond the deepest rung, below it and above it.
Optionalupper
One boxen (letter-value) plot: a median, a ladder of quantile pairs around it, and whatever fell outside the deepest rung.
A box plot's five-number summary is this shape with exactly one rung, and that fixed depth is the reason it cannot express a boxen: the point of a letter-value plot is that a large sample gets more rungs, so the tails stay legible instead of collapsing into a whisker and a scatter of dots.