must be valid

基本解释

Furthermore, it defines a special QName data type for strings that must be valid as qualified names.
而且，它为必须是有效限定名的字符串定义了一个专门的 QName 数据类型。
DB2 UDB does not allow MAXVALUE to be followed by any other values, and the range must be valid for each partition value.
DB2 UDB 不允许 MAXVALUE 后面跟上任何其他值，每个分区值的范围必须有效。
For the element message to be valid, its content must be valid as defined by its complexType definition and all assertions must evaluate to true.
要使 message 元素有效，其内容必须按照 complexType 定义那样定义为有效内容，并且所有断言的值必须为 true。

What must this experiment have the potential to do, to be a valid scientific experiment?
实验必须有做什么的能力,才能被称为一个有效的科学实验呢？
麻省理工公开课 - 计算机科学及编程导论课程节选

The ruling says that 1.1 million signatures might be valid but must be verified by the signers.
CENTERFORSECURITYPOLICY: Hemispheric security watch
What is more, the Parliament is engaged in predictable manuevers to dilute the effect of the referendum by adding questions to the ballot — thereby deliberately confusing the outcome and by requiring that at least 50 percent of registered voters must participate in order for it to be judged valid.
CENTERFORSECURITYPOLICY: Freedom Flame 2013