This is another form of capped sale, but in this case, the portion of tokens sold to participants is dependent on the length of the sale. If all tokens are sold on day one, then a proportion, P %, would be distributed among participants, and the rest retained by the project team. If the sale finishes on day two, then P+X % would be distributed, and so on. The idea in this type of auction is to guarantee that if a participant buys at time T, then they are buying at a value that is at most 1 / T. The reality often doesn't match the theory, as was shown with the Gnosis token sale, where the fear of missing out caused everyone to buy in at day one, and the sale therefore finished earlier than expected.