. How Documents Know Their Parents Every operating system needs a mechanism to associate documents with the applications that created them. | . How Documents Know Their Parents Every operating system needs a mechanism to associate documents with the applications that created them. When you double-click a Microsoft Word document icon for example it s clear that you want Microsoft Word to launch and open the document. So how does Mac OS X know how to find a document s mommy It actually has four different mechanisms. Your preferences. If you ve used the Always Open with command to specify a program Section that s the one that opens. Type Creator codes. First it checks to see if the document has an invisible four-letter Type code and Creator code. It does that because that s how Mac OS 9 used to recognize documents and Mac OS X wants to ensure compatibility. Apple used to monitor and track these four-letter codes in conjunction with the various Mac software companies so that no two creator codes were alike. The Creator code is the same for a program and the documents it creates MSWD for Microsoft Word FMP7 for FileMaker Pro and so on. That s the entire point The creator code tells the Mac which program to open when you double-click a particular document. The Type code meanwhile specifies the document s file format GIF JPEG TIFF and so on. UP TO SPEED Window Layering Mac OS X takes a layered approach to your programs windows. They re not all in front or all in back it s entirely possible to wind up with the windows of different programs sandwiched and layered front to back. Suppose for example you have Microsoft Excel in the foreground but Word in the back-ground. If you click within a visible portion of a background window you bring only that window of Word to the front. The remedy for this situation if it bothers you is the Window Bring All to Front command which appears in the Finder and many other programs. It brings all of a program s windows to the front. You can do the same thing by simply clicking the program s Dock icon or using the -Tab heads-up display. In the Finder if you prefer you .
