Extensions

Extensions

Windows contains several file types whose extensions can remain hidden in File Explorer even when normal file extensions are enabled.

The project handles these types by modifying their corresponding registry classes.

Basic extensions

The standard script processes the following classes:

Extension	Registry class	Description
.lnk	HKEY_CLASSES_ROOT\lnkfile	Windows shortcut
.url	HKEY_CLASSES_ROOT\InternetShortcut	Internet shortcut
.pif	HKEY_CLASSES_ROOT\piffile	Program Information File
.scf	HKEY_CLASSES_ROOT\SHCmdFile	Windows Explorer command file
.library-ms	HKEY_CLASSES_ROOT\LibraryFolder	Windows Library file
.website	HKEY_CLASSES_ROOT\Microsoft.Website	Website shortcut
.searchconnector-ms	HKEY_CLASSES_ROOT\SearchConnectorFolder	Search connector
.search-ms	HKEY_CLASSES_ROOT\SearchFolder	Saved Windows search
.SettingContent-ms	HKEY_CLASSES_ROOT\SettingContent	Windows settings content

These classes correspond to the list currently defined in ShowHiddenExtensions.bat.

---

.lnk

.lnk files are standard Windows shortcuts.

Windows treats this file type specially and normally hides the extension through the :

HKEY_CLASSES_ROOT\lnkfile

The relevant registry behavior is associated with NeverShowExt.

Example:

Document.pdf

versus:

Document.pdf.lnk

With the extension hidden, the second file may visually appear as Document.pdf even though it is actually a shortcut.

.url

.url files are Internet Shortcut files.

The main class used by the script is:

HKEY_CLASSES_ROOT\InternetShortcut

Some Windows installations may also involve other URL association classes, so .url behavior can vary between systems.

.pif

.pif files originate from the Windows Program Information File mechanism.

The associated registry class is:

HKEY_CLASSES_ROOT\piffile

Although largely a legacy format, the file type remains part of Windows compatibility behavior.

.scf

.scf files are Shell Command Files associated with Windows Explorer.

The corresponding registry class is:

HKEY_CLASSES_ROOT\SHCmdFile

These files are another example of an extension that can remain hidden independently of the normal Explorer extension setting.

.library-ms

Windows Libraries use the .library-ms file format.

The corresponding registry class is:

HKEY_CLASSES_ROOT\LibraryFolder

Library files are commonly stored in the user's Windows Libraries directory.

.website

The project also processes:

HKEY_CLASSES_ROOT\Microsoft.Website

which is associated with Windows website shortcut behavior.

.searchconnector-ms

Search Connector files use:

HKEY_CLASSES_ROOT\SearchConnectorFolder

They are part of the Windows search integration mechanism.

.search-ms

Saved Windows searches use the:

HKEY_CLASSES_ROOT\SearchFolder

Microsoft has historically documented .search-ms as a distinct Windows file type and security-relevant shell file format.

.SettingContent-ms

Windows settings shortcuts use the:

HKEY_CLASSES_ROOT\SettingContent

The file type is associated with Windows settings/content shortcuts.

---

Extended extensions

ShowHiddenExtensions-extended.bat additionally attempts to process several CLSID-based entries.

Extension	Registry class	Description
.mydocs	CLSID{ECF03A32-103D-11d2-854D-006008059367}	My Documents drop target
.ZFSendToTarget	CLSID{888DCA60-FC0A-11CF-8F0F-00C04FD7D062}	Compressed Folder SendTo target
.MAPIMail	CLSID{9E56BE60-C50F-11CF-9A2C-00A0C90A90CE}	Mail service
.DeskLink	CLSID{9E56BE61-C50F-11CF-9A2C-00A0C90A90CE}	Desktop shortcut

These entries correspond to legacy Windows shell/COM registrations. The associated extension relationships can be found in registry-extension databases as well.

The extended script currently requires system-level access for these entries and should therefore be considered experimental.

Basic vs Extended

The distinction is therefore:

Basic
├── Explorer settings
├── .lnk
├── .url
├── .pif
├── .scf
├── .library-ms
├── .website
├── .searchconnector-ms
├── .search-ms
└── .SettingContent-ms

Extended
└── Everything above
    ├── .mydocs
    ├── .ZFSendToTarget
    ├── .MAPIMail
    └── .DeskLink

The basic script is the main supported implementation, while the extended version is intended to cover additional legacy/system entries.