Extend-o-matic

An extension is a piece of software that can be added to a Macromedia application to enhance the application’s capabilities. Adobe offers several types of extensions for its various products such as Dreamweaver and Flash. Quoth Adobe: “…Flash extensions include components that you can use to build projects, templates for designing Flash content, reusable ActionScript code snippets, additional symbol libraries, and more.”

Creating an MXP file is essentially a two-step process.

1. Create an MXI file, which will be the source file you will work with. This is essentially an XML document that explains which files will be included in your extension and where they should be placed when the extension is installed. Adobe includes a few examples, as well as a blank template:

C:\Program Files\Macromedia\Extension Manager\Samples

2. The second step is to properly package the MXI file into an MXP file. Save the MXI file into the same folder with the any other files you want to package. Then open the Extension Manager and use the following steps to package the extension into an MXP file.

Select Files > Package Extensions

I gleaned much of the above from this article on Fireworks. Also, Adobe has a rather large (but good – and amusing in places!) manual, entitled The Extension Installation File Format.