Adding Application Substitution Links:

When you double-click on a document that the Finder does not recognize, it displays an Application Not Found dialog and refuses to open the document. By adding application substitution links, you can substitute an application for the missing application. That way, you can double-click on those documents and they will automatically open the application of your choice. Personally, I’ve defined links for QuickTime movies, Stuffit 1.5.1 and Deluxe archives, Compactor documents, Text files, PICT files, and MacWrite documents.

With the System 7 Pack!, you’ll simply match document types to a substitute application. The System 7 Pack! will do the rest.

As an example, we’ll substitute Microsoft Word for MacWrite documents. Once we define this link, you’ll be able to double-click on MacWrite files from the Finder and your Mac will automatically open them in MS Word. 

1) To add a link, click on the Add Link… button. A dialog box will appear.
a) If you know the document type and application creator that you want to link together, type them here. (In our example, you would type WORD in the Type Box and MSWD in the Creator box. WORD is the document type for MacWrite documents. MSWD is the creator of Microsoft Word.) Press OK to save your changes and dismiss the dialog box.
b) If you do not know these 4 letter codes, you can let the System 7 Pack! get them for you. 
c) Click on the Document button and select a representative document for the document type. (In our example, you would select a MacWrite document.)
d) Next, click on the Application button and select the application you’d like to open these documents with. (In our example, you would find Microsoft Word on your disk and select it.)
2) To remove a link, select a link from the Substitutions list and click on the Remove Link button. The System 7 Pack! will remove the link from the list.
3) You’ll probably also want to uncheck the Show Application Substitution Dialog box. Please read the Dialogs Section above for more information on this feature.