每个文档还可以包含元数据(关于数据的数据)，比如惟一的文档id和修改号。

Each document also contains metadata (data about the data), such as a unique document ID and revision Numbers.

youdao

每个文档还可以包含元数据(关于数据的数据)，比如惟一的文档id和修改号。

Each document also contains metadata (data about the data), such as a unique document ID and revision Numbers.

youdao