Windows registry structure: default value

A registry key can have an unnamed value: the default value.

Accessing default values in the command line

When using reg.exe, default values are specified with the /ve flag:

C:\> reg query HKCU\AppEvents\EventLabels\Open /ve

There are two ways to query the default value in PowerShell:

PS C:\> (get-itemProperty hkcu:\AppEvents\EventLabels\Open)."(default)"
PS C:\> (get-item hkcu:\AppEvents\EventLabels\Open).getValue('')

Similarly, the default value can be assigned PowerShell with

PS C:\> set-item hkcu:\AppEvents\EventLabels\Open -value '…'

A key's default value can be deleted as shown below. The key (subkey named '') must be opened writable by setting the second parameter to $true:

(get-item 'hkcu:\Software\tq84').OpenSubKey('', $true).DeleteValue('')