For example, in the 99-00 season, teams can send away the first-round draft pick in 2000, regardless of whether they have the first-round draft pick in 1999, because the draft pick in 1999 is no longer a "future" draft pick. But they can't exchange first-round draft picks at 00 and 0 1. This is why many teams sell draft picks every other year. In addition, as long as the team has the first round draft right of the year, whether it is won by itself or obtained from other teams during the transfer, it can be counted. As long as there is one, it doesn't matter if all the others are sold.
The introduction of this rule was partly due to the operation of the Cleveland Cavaliers in the early 1980s. From 1980 to 1983, Ted Stephon was the owner of the Cleveland Cavaliers. He operated a series of questionable player transactions that left the Cavaliers without the first-round draft pick for several years. Stepan's failed player trading actions almost ruined the Cavaliers. In the end, the NBA had to put pressure on Stepan to sell the Cavaliers, and then Cleveland local rich Gordon Gunder became the owner of the Cavaliers. In order to facilitate this transaction, the NBA gave the Cavaliers several future draft picks. This rule is only valid for the "future" draft.