This section explains how you can package and distribute your customizations (such as custom commands, custom operators, and custom filters) as add-on packages (.xsiaddon files).
An .xsiaddon file provides an easy way to distribute customizations, especially to external users (for internal users, you can use workgroups to deploy your customizations).
If you intend to distribute add-on packages, the recommended way to develop your add-ons is to use a workgroup, and to create a separate Add-on directory for each add-on. Developing add-ons in Add-on directories allows you to package add-ons by location: Softimage can create an .xsiaddon file that contains all the files and folders in a specified location. So instead of adding files one-by-one to an add-on package, you can simply specify a folder and everything in that folder is put in the add-on package.
Users who want to upgrade their copy of the add-on should uninstall the old .xsiaddon first, then install the latest .xsiaddon.
Autodesk Softimage 2011