This expression must identify a single element or attribute whose content or value is used for the constraint.

该表达式必须标识其内容或值用于约束的单个元素或特性。

youdao

This expression must identify a single element or attribute whose content or value is used for the constraint.

该表达式必须标识其内容或值用于约束的单个元素或特性。

youdao