Which MIME types are related to file extension ".mst"?
The .mst file extension is associated with 4 MIME types:
application/x-ms-installer, application/x-msi, application/x-windows-installer, application/x-ms-mst.
A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.
About .mst Files
MST files are transform files used in Microsoft Windows Installer setups. They store custom modifications that adjust an MSI package during installation.
They carry MIME types such as application/x-ms-installer, application/x-msi, application/x-windows-installer, and application/x-ms-mst. These indicate that MST files work closely with the installer engine to apply modification scripts without altering the original MSI package.
The main use of MST files is to customize software installations. This includes:
- Customization: Change default settings and dialogs during installation.
- Configuration: Apply patches, registry changes, or extra features tailored to specific needs.
- Deployment: Streamline enterprise installations by applying uniform settings across many systems.
Relationship between file extension and MIME type
A file extension is a suffix at the end of a filename that indicates what type of file it is. File extensions help both users and operating systems identify what application should be used to open the file.
File extensions are typically separated from the filename by a period (dot) and consist of 2-4 characters, though they can be longer. For example, in the filename "document.pdf", ".pdf" is the file extension.
File extensions are closely related to MIME types, as they both serve to identify the format of a file. However, while MIME types are used primarily by web browsers and servers, file extensions are used by operating systems and applications.
Associated MIME types
application/x-ms-installer, application/x-msi, application/x-windows-installer, application/x-ms-mst
FAQs
What is an MST file and what is it used for?
An MST file is a Windows Installer Transform file used to modify the behavior of an .msi installation package. It allows administrators to customize setup options—such as accepting license agreements, entering product keys, or disabling specific features—without altering the original vendor-supplied MSI file.
How do I open or edit an MST file?
You cannot open an MST file with a standard text editor; you need a specialized database editor. The most common tool is Microsoft Orca, which is included in the Windows SDK. Third-party tools like InstEd or Master Packager are also popular for viewing and editing the tables inside an MST.
How do I apply an MST file to an MSI installer?
You apply a transform using the Windows Installer command line interface. The standard syntax is msiexec /i setup.msi TRANSFORMS=mychanges.mst. This command tells the system to launch the installer and immediately apply the customizations defined in the MST file.
Why can't I double-click an MST file to run it?
MST files are not standalone executables; they contain only configuration data (deltas) meant to modify a specific MSI package. Because they rely on the base MSI to function, the operating system does not know how to execute them directly when double-clicked.
What is the difference between MSI and MST files?
An MSI file is the complete installation database containing files, registry keys, and logic. An MST file is a small overlay that contains only the changes to that database. Think of the MSI as the "base" document and the MST as a "patch" applied during installation.
Can I merge an MST file permanently into an MSI?
Yes, this is often called "transplanting" or merging a transform. Using a tool like Orca, you can open the base MSI, apply the transform via the menu, and then use "Save As" to create a new MSI file that has the MST changes permanently embedded.
What MIME type should be configured for MST files?
When hosting these files for download or deployment, the specific MIME type application/x-ms-mst is often used. However, they are frequently associated with generic installer types like application/x-ms-installer or application/octet-stream on web servers.
General FAQ
What is a MIME type?
A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.
MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.
MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.
How do I find the MIME type for a file?
You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.
Why can one extension have multiple MIME types?
Different programs and historical usage may assign various MIME identifiers to the same file format. Listing them together helps maintain compatibility across tools.