It shows that the credit card has been spent 9900 yuan, and now the credit card limit is 100 yuan. Another possibility is that there are other credit cards in the bank, so several credit cards share one line.

Shared credit line means that all credit cards held by the same cardholder use the same credit line. For example, if you hold five credit cards of a bank with a credit line of 10000 yuan, then the shared credit line of these five credit cards is 10000 yuan. When you overdraw 2000 yuan with one card, you can overdraw 8000 yuan with the other four cards.

Extended explanation: Credit line sharing means that credit cards of the same bank and brand share the same credit line (generally the highest credit line for one card). Although several cards have their own single credit limit, the total overdraft in use cannot exceed the shared credit limit of the brand credit card.