Parameters that are mandatory and accept values based on position are written as follows:

SYNTAX
    Get-ADUser [-Identity] <ADUser> ...

In this case, the Identity parameter name is optional but the value is not. The command may be used as described by either of the following examples:

Get-ADUser -Identity useridentity 
Get-ADUser useridentity 

In both cases, the supplied value fills the Identity parameter.

A command with more than one mandatory positional parameter may appear as follows:

SYNTAX
    Add-Member [-NotePropertyName] <String> [-NotePropertyValue] 
    <Object> ...

In this case, the command may be called as follows:

Add-Member -NotePropertyName Name -NotePropertyValue "value" 
Add-Member -NotePropertyValue "value" -NotePropertyName Name 
Add-Member Name -NotePropertyValue "value" 
Add-Member Name "value"