This is the built-in help made by Microsoft for the document 'about_Ref', in PowerShell version 5 - as retrieved from
Windows version 'Microsoft Windows Server 2012 R2 Standard' PowerShell help files on 2016-06-24.
For PowerShell version 3 and up, where you have Update-Help, this command was run just before creating the web pages from the help files.
Describes how to create and use a reference variable type.
You can use the reference variable type to permit a method to change the
value of a variable that is passed to it.
When the [ref] type is associated with an object, it returns a reference
to that object. If the reference is used with a method, the method can
refer to the object that was passed to it. If the object is changed within
the method, the change appears as a change in the value of the variable
when control returns to the calling method.
To use referencing, the parameter must be a reference variable. If it is
not, an InvalidArgument exception is thrown.
The parameters used in method invocations must match the type required
by the methods.
PS> function swap([ref]$a,[ref]$b)
>> $a.value,$b.value = $b.value,$a.value
PS> $a = 1
PS> $b = 10
PS> swap ([ref]$a) ([ref]$b)
PS C:\ps-test> function double
>> param ([ref]$x) $x.value = $x.value * 2
PS C:> $number = 8
PS C:> $number
PS C> double ([ref]$number)
PS C> $number
The variable must be a reference variable.
PS C:\ps-test> double $number
double : Reference type is expected in argument.
At line:1 char:7
+ double <<<< $number