Also, when multiple things can occur inside an element, the order of occurrence can be specified or left open, as needed.

另外，当在一个元素中可以出现多个事物时，还可以指定出现的顺序(或按照需要不指定)。

youdao

These rules describe, for example, which elements are valid, the order of elements within a document, the data types of attributes, whether an element is required or optional, and so on.

这些规则定义哪些元素是有效的、文档中元素的次序、属性的数据类型、一个元素是必需的还是可选的等等。

youdao

The specified order of the sequence of assertions is insignificant as all assertions in this sequence need to evaluate to true for an element or attribute of this type to be valid.

断言序列的具体顺序并不重要，因为序列中所有断言的值必须为 true，这样该类型的元素或属性才是有效的。

youdao

"The technology hasn't necessarily been overhyped but there is an element of 3D printer makers over-claiming in order to sell their devices, " he said.

BBC: Has 3D printing in the home been over-hyped?

Mr. DIAMOND: That's true, and we have many different type of wars, and one of them is an insurgency against the new political order with a heavy terrorist element that aims to strike at Europe and the United States.

NPR: Is Victory in Iraq Still Possible?