AOCE's Open Directory and related software introduced the concept of directory entries (such as business cards) as first-class desktop objects. This is used to create a drag-and-drop metaphor for mail, fax, and other directory-based activities. Each endpoint, a mail server for instance, is driven by a plug-in extension that is driven by a common AOCE-supplied queue and queue viewer. PowerTalk provides a set of standard forms for interacting with the items in the queues, and a common interface for mail, and a universal mailbox. Encryption is supported by a single keychain that remembered all your passwords and digital signatures, encrypting them together so only a single password needed to be remembered.