Essentials are an extension to ProR that contain useful functionality, but are not part the Eclipse distribution. Features include: XHTML support (formatted text) and Suspect Links (set a flag if source or target of a link changes).

Essentials are free and can be installed via Help | Install new Software... Select ProR Essentials from the "Work with:" dropwdown and follow the standard installation procedure.

More information can be found at the ProR Essentials site.

The ProR Platform for Requirements Engineering and Formal Modeling

ProR is a tool for requirements engineering that supports the ReqIF 1.0.1 Standard natively. It is Eclipse-based and is built for extensibility.