# Bitable app_token generation rule changes

### Details
The document identifier (app_token) of Bitable will always start with the prefix of bas before. Starting from February 1, 2023, the app_token will no longer be fixed with bas as the fixed prefix.

### Impacts
After the platform is upgraded, the app_token of the newly created Bitable no longer starts with bas. If the developer's business logic still uses prefix matching to determine the unique identifier of Bitable, it may cause errors.

### How to adapt to the change
In order not to affect the normal business of developers, please no longer use string matching to judge app_token, and remove the judgment of the fixed prefix bas.

<br> For adaptation assistance, please contact [technical support](https://applink.feishu.cn/TLJsX982).