1. Payment obligations can be divided into primary payment obligations and secondary payment obligations.

1) The so-called principal payment obligation, referred to as principal obligation, refers to the basic obligation that is inherent and necessary in the contractual relationship and is used to determine the type of contract.

For example, in a sales contract, the seller has the obligation to deliver the object and transfer its ownership, and the buyer has the obligation to pay the price, which are both principal payment obligations. As far as a bilateral contract is concerned, this type of principal payment obligation constitutes a contingency payment obligation. The other party may refuse to perform its own performance before payment is made. If part or all of the performance cannot be performed due to reasons not attributable to both parties, one party shall be reduced to or exempted from its obligation to provide cessation of payment. When performance cannot be performed, performance is delayed, or performance is incomplete due to reasons attributable to the debtor, the creditor may request compensation for losses and terminate the contract.

2) The so-called secondary payment obligations, referred to as secondary obligations, are obligations that do not have independent meaning and only have the function of subsidizing the main payment obligation. The purpose of its existence is not to determine the type of contract, but to ensure that the interests of creditors can be maximized.

Payment obligations can also be divided into original payment obligations and secondary payment obligations.

1) The original payment obligation, also known as the first payment obligation, refers to the original obligation in the contract. If the seller of a famous horse delivers the horse and transfers its ownership (primary payment obligation), and delivers the horse's pedigree certificate (secondary payment obligation), it is the original payment obligation.

2) The secondary payment obligation, also known as the second payment obligation, is an obligation that arises due to the evolution of special events during the performance of the original payment obligation. It mainly includes: the obligation to compensate for losses arising from the inability to perform, overdue performance or incomplete performance of the original payment obligation; the obligation to restore the original status when the contract is terminated.

The above-mentioned payment obligation is based on a contractual relationship. Although the content of the contractual relationship has changed or expanded as a result, its identity remains unchanged