Customize Existing Products
Documentum's client products include a set of Microsoft Windows-based integrations collectively known as the Desktop Client. The Windows' clients include an integration into Windows Explorer and the Microsoft Office suite of programs. The Windows-based integrations all make use of a common set of COM-based components. Each component implements a single piece of content management functionality, (checkin, view/edit properties, etc).The Visual Basic source code for these components is made available to allow for customizations. Also the C++ source code for the Office integration is available.

Build Custom Application
In order to communicate with the Content Server you will need to make use of the Documentum Foundation Classes, (DFC). You can either make calls directly to the DFC or through the Business Objects Framework, which is a DFC extension.

The DFC libraries are a set of Java classes that provide access to Content Server functionality. A COM bridge for the DFC exists which means that applications can be written in any COM or Java-compliant language. A .NET Primary Interop Assembly (PIA) is available that allows developers to access DFC from .NET