The group is currently working on a formal data model for genealogical data. In addition to the Model description, there are two associated diagrams.
Versions are available for most hardware and software platforms.
Note that when viewing the diagrams within your browser, the fine print might be pretty fine. The zipped description document is in Microsoft Word 97 format. Please be aware that neither Microsoft's conversion add-on for Word 95, nor Corel's Word 97 import feature handle the complexities of the document very well. The zipped diagram and process charts are in Visio 5 format, which is the original format for the two diagrams.