Median, low and high are the middle, the 5th and the 95th percentile of the results in the range (the lowest and highest when there are fewer than five). A change compares the median of the last 7 or 30 days with the 7 or 30 days before, from dated results, and needs at least three in each period.
Auction prices are hammer prices as each platform reports them, which usually leave out the buyer's premium. Dealer sales are completed sales on dealer marketplaces. On sale counts the lots live now across the index. The 5 weeks line is the weekly median, Monday to Sunday.
With price channels, a result outside its reference's channel (its results' median around the day, times or divided by 1.3) is left out of every median.