File Types

This information does not apply to InstallScript or InstallScript Object projects.

If your application manipulates files with a unique file extension, you can register your file type in the File Types view, which is available as an advanced setting within the Components view and the Setup Design view (for installation projects only). For example, if your application manipulates files with the .xyz extension, registering the file type instructs the operating system to open the file with your application when the user double-clicks its icon.

This advanced setting registers the following information about a file type on the target system when the component is installed or advertised:

File Type Information
Information Registered	Description
File Extensions	You can associate file extensions (such as .doc and .txt) with the component's key file.
ProgIDs	By setting the ProgID property in the extension, you can name a ProgID—for example, extfile—that will contain the file type registration.
Verbs	You can register command verbs (such as Open and Print) that appear in the context menu that Windows Explorer displays when an end user right-clicks a file with the current extension.
MIME Type	You can also register multipurpose Internet mail extension (MIME) types, also known as media types or content types, for the component's key file. You can also associate a MIME type with a class ID.

On Windows NT 4 and Windows 9x systems, file association information is stored under the root HKEY_CLASSES_ROOT. On systems running Windows 2000 or later, file associations are stored in both HKLM\SOFTWARE\Classes and HKCU\SOFTWARE\Classes; you can see a merged view of the data under HKEY_CLASSES_ROOT. It is recommended that you use the File Types editor instead of writing directly to the registry to support Windows Installer advertisement features.

Note also that Windows Installer writes file-extension advertisement information to the registry, which appears to be a string of random characters. This behavior is normal.