For example, there might be a set of permissions for videoconferencing applets, which would include things like permission to use the camera, the microphone, the speaker, the display, and networking access. For example, all programs from a company intranet signed by the system administrator's key might comprise a zone. Policies can then be defined on a per-zone basis. Sun has a system of implication in which permission for code to use one resource can imply permission to use another resource. All of these are examples of grouping signers or privileges together and treating the group as a unit.
Fewer decisions means more attention paid to each decision and hence, better decisions.
A digitally signed applet can be treated as trusted local code as long as the signature key is recognized as trusted by the system finally running the code. All rights reserved.