Value types of arguments (the type of value expected by a parameter) are enclosed in angular brackets, as shown in the following example:
<string> <string[]>
If a value is in the <string> form, a single value is expected. If the value is in the <string[]> form, an array (or list) of values is expected.
For example, Get-CimInstance accepts a single value only for the ClassName parameter:
SYNTAX
Get-CimInstance [-ClassName] <String> ...
The command may be called the same as the following:
Get-CimInstance -ClassName Win32_OperatingSystem
In comparison, Get-Process accepts multiple values for the Name parameter:
SYNTAX
Get-Process [[-Name] <String[]>] ...
Get-Process may be called the same as the following:
Get-Process -Name powershell, explorer, smss