The $_ is another specialvariable that has different meanings in different contexts.
$_ 是另一个在不同上下文中有不同含义的特殊变量。
2
You don't have to declare a specialvariable for it if you don't care about its actual value.
你并不需要为它声明一个特定的变量,如果你不关心它的实际值。
3
A collaboration scope also includes a specialvariable called a collaboration folder, which can be used to attach document links to the business process.