The Unrealised Profit and Loss metric calculates the net Profit of Loss of the aggregate market by taking the difference between the Market Cap and the Realised cost basis (normalised by Market Cap to form an oscillator). For Decred, coins are constantly on the move in tickets and in CoinShuffle++ mix transactions. Each time DCR is moved on chain, there is an explicit decision and opportunity cost to sell the coins, or not. Therefore, this metric should be interpreted to capture the profit and loss incurred since the last time DCR holders, on aggregate, interacted with their coins.
Where the metric is positive, it indicates that market pricing is above the aggregate 'recency bias' level of the Realised Cap and conversely, when the metric is negative, market pricing is below the aggregate 'recency bias' level. Periods of extreme diversion from the Realised Cap mean (+- 50% PnL) are highlighted as Euphoria and Capitulation respectively.
Data Source: Coinmetrics.io.