The first basic principle is that the wages of players on both sides of the transaction should be basically equal, within 25%+ 10W. For example, the Celtics need five players to make up Garnett's salary, or the Mavericks sign Van Horne with a temporary high salary. In order to balance the salary, some teams often let the third party participate in the transaction.
The special case is that if one of the two teams is below the salary cap, the difference can be the part where they are below the salary cap. An example is that the Clippers traded Camby this year.
Secondly, the draft sign or the draft sign right and cash can participate in the transaction without calculating the salary, but these can be used as things to balance the value of both parties. For example, the Lakers traded a draft pick and Gasol's draft signing right for Gasol.
Third, we need to know the special terms of the transaction. This thing is produced between two transactions with a large span in some teams. Some people call it "credit point". Simply put, it is to balance wages. If there is a big difference in the annual salary of the players traded by both parties, it can be balanced through the special terms of the transaction. In addition, this special clause will not be included in the team's salary space after the exchange, so many teams use it in exchange for reducing the total salary.
Let's learn about this first. Of course, there will be many unusual rules, such as a non-tradable clause in Kobe's contract and so on. However, if you understand the above, you can basically know the whole.
They are all summed up by themselves, and some places may be difficult to understand.