An envelope is an object that deforms automatically, based on the movement of its skeleton or other deformers. You can:
• Assign an object as an envelope on a set of deformers, like bones. Each point in the object is assigned an initial weight to various deformers.
• Use bounding volumes to modify how points are assigned.
• Manually assign specific points to specific deformers.
• Modify how points are weighted, either numerically or by painting.
• Change the reference pose used to calculate the initial weights.
• Add or remove deformers from an envelope.
Autodesk Softimage v.7.5