PROMPT allows you to create a structural diff of two ontologies (this component of PROMPT is called PromptDiff). It presents two views if the diff. In the first view (Tree view), you see the class tree for your current ontology, with new frames underlined, deleted frames crossed out, moved and changed frames shown in different fonts and colors. The tooltips provide additional information about the change. When you select a class, you see not only the class form on the right-hand side, but also a table comparing the current frame to its old version. You can accept or reject tha changes at various levels of granularity. In the secont view (Table view), you see a list of frames from the two versions side-by-side, with additional information in other columns and an individual diff.
Protege facilitates reuse and development of ontologies through the project-inclusion mechanism: One project can include one or several other projects and reuse all frames from the included projects. For example, you can develop a general ontology and then include it in the more specific one to provide structure for the latter. You can also include the same project in several others, ensuring that they all get the same copy. The "moving frames" mode of the PROMPT tab allows you to move frames between projects, thus altering both. When moving a frame to the including project, you can choose everything that must be moved in order for the projects to remain consistent: An included project should always stand on its own, therefore, no frame in the included project should reference a frame in the including project. You can also choose to perform the process frame-by-frame. There is a running list of conflicts to help you sever all the links from included to including project in the latter mode.
PROMPT is an interactive ontology-merging tool. It guides you through the merging process making suggestions, determining conflicts, and proposing conflict-resolution strategies. The initial suggestions are based on the linguistic similarity of the frame names. After the user selects an operation to perform, PROMPT determines the conflicts in the merged ontology that the operation have caused and proposes possible solutions to the conflict. It then considers the structure of the ontology around the arguments to the latest operations—relations among the arguments and other concepts in the ontology—and proposes other operations that the user should perform.
Sometimes, you may want to save only part of your ontology for various reasons: use some subset of the knowledge base in a different project, distribute only part of your ontology, debug a smaller portion of it, and so on. The PROMPT taballows you to pick and choose frames and then copy them into your local project. You can choose a frame and copy everything related to the frame (the transitive closure of what it refers to, except for the subclasses - otherwise you'll always get the whole knowledge base). Or, you can copy frames one by one - you'll get a list of frames you are referring to that you have not copied.