通常可以看作插入结构，因为把这样的结构去掉之后句子仍然完整。类似的句型还有：what we used to call, what is called, what they described as, what can be called, what they regarded as, as we call it, as we know it等。通常翻译为“所谓的…”，可以按照英语原文顺序直接翻译。