A file's file type describes the data
that the file contains. File types are used by the system - and
Tracker in particular
- to figure out how to deal with a file. For example, the file type
determines which application opens a file when you double-click
it. FileTypes lets you change the characteristics that pertain to
a particular file type, and also lets you set the file types of
specific files.
When you launch FileTypes
you see this window:

The left side of the window
is a scrolling list of all the file types known to your system.
File types are broken into broad categories (application, audio,
image, etc.). The system adds new file types automatically when
you install new applications; you can also manually add and remove
types from the list via the dialogs accessed through the Add...
and Remove buttons beneath the scrolling list.
A file type is associated
with the icon that appears in the Icon box. Double-clicking in the
Icon box (which will be empty if the type doesn't yet have an icon)
launches the Icon-O-Matic application, which lets you create and
modify icons.
The File Extensions section displays the file name extensions (such
as ".html", ".gif", and so on) that are associated
with a file type. If a file doesn't have a file type assigned to
it already, the system will look at the file's extension to try
figure out what the type should be. After the type is assigned,
the file's extension is ignored (by the file-typing mechanism).
The file type Description
is a human-readable description of a file type.
The Preferred Application is the app that's launched when you double-click
a file of the given type. See "The FileType Add-on" section,
below, for a description of ways to do this.
The Extra Attributes section lists the additional attributes that
are associated with a file type. A Tracker window knows how to display
these extra attributes when it's in List View mode. Although you
can add and remove attributes yourself, it's best to leave these
operations to applications and the system.
The FileType
Add-on
Another way to access FileTypes is to use the FileType add-on in
a Tracker window. This is a convenient way to change the file type,
or other characteristic, of a specific file.
To launch the add-on,
open a Tracker window, highlight one or more files, and select Add-Ons
> FileType from the window's File menu or from the file's context
menu.
In the File Type section
is the file type associated with the file(s). There are four ways
to change the type:
- Enter (as text) the file type in the text field.
- Click Select... and choose a type from the list of
all types known to the system.
- Click Same as... to make the type of this file the
same as some other file (which you choose from the file selection
panel that's displayed).
- Drag and drop a file onto the File Type section of the panel;
the file that you're examining assumes the type of the dropped
file.
The Preferred Application
section of the dialog lets you associate a particular application
with the file(s) in one of these ways:
- Choose an application from the popup menu.
- Click Select... to bring up a file selection panel,
and choose an application by locating it in the file system.
- Make it the same as the application associated with another
file via the Same as... button.
- Drag and drop the desired application onto the Preferred Application
section of the window.
The box on the right
side of the window displays the file's icon (if it has one). To
create a new icon or edit the existing one, double-click inside
the box to launch the Icon-O-Matic application.

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