ecma标准文档阅读问题，一个隐藏操作前面带一个问号表示什么意思？

Question

https://tc39.github.io/ecma262/#sec-bitwise-not-operator

    Runtime Semantics: Evaluation#
    
    UnaryExpression:~UnaryExpression
    Let expr be the result of evaluating UnaryExpression.
    Let oldValue be ? ToInt32(? GetValue(expr)).
    Return the result of applying bitwise complement to oldValue. The result is a signed 32-bit integer.
    

这里面 ? GetValue(expr) 前面为什么要带个问号？表示什么意思？ ? ToInt32前面也带了。

Answer 1

自己找到了

https://tc39.github.io/ecma262/#sec-algorithm-conventions

    Abstract operations referenced using the functional application style and the method application style that are prefixed by ? indicate that ReturnIfAbrupt should be applied to the resulting Completion Record. For example, ? operationName() is equivalent to ReturnIfAbrupt(operationName()). Similarly, ? someValue.operationName() is equivalent to ReturnIfAbrupt(someValue.operationName()).