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Welcome!

This website is dedicated to the topic of data models used in genealogy.

First, a word about terminology. The term "object model" more accurately describes our focus. This is because a UML model decomposes genealogical systems into objects which have behavior and attributes. The attributes (or data) represent only one aspect of an object.

Why study object models?

Object models are like blueprints for software. They help a software developer break down complex programs into manageable components and objects. They also help the designer visualize the relationships between the various objects and what information the objects may share. It is much easier to produce several alternative software blueprints and discuss their pros and cons than it is to make changes to the software later when the program has already been built.

Another important reason for working with object models, is that it allows "domain experts" to have influence over the outcome. In this case the "domain expert" is a professional genealogist or genealogy enthusiast, who want the software to support certain "standard practices" in their specialty. By engaging the experts early on, the design accomodates the needs of end users.

So what kinds of data and object models exist?

There is a data model developed by the GENTECH Lexicon Working Group, called the "GENTECH Genealogical Data Model Phase 1" (hereafter referred to as GENTECH-GDM). For more about it, see the GENTECH-GDM section.

The GenXML specification at the GenXML website, defines a file format for exchange of genealogical data. This XML schema is influenced by the GENTECH Genealogical Data Model.

The gdmxml specification at the gdmxml website, defines an XML implementation of the GENTECH Genealogical Data Model. "Specifically, it is a RELAX NG Schema to validate XML documents with genealogical information according to the Genealogical Data Model put together by the Lexicon Group from GENTECH."

The GEDCOM interchange format, the defacto standard today, was developed by the Family History Department of The Church of Jesus Christ of Latter-day Saints (LDS Church). This is the file format exported by most genealogy applications and it follows the GEDCOM version 5.5 (1996) and/or 5.5.1 (1999 draft) specifications. For more about the underlying object model, see the GEDCOM-UML section. For a SQL DDL representation of GEDCOM, see the GEDCOM-DDL section.

The GEDCOM XML Specification Release 6.0 was available from the LDS Church as the file GedXML60.pdf This is a DTD for GEDCOM content. It was considered a "beta" version which was released December 6, 2002. The FamilySearch.org website indicates that this specification is not in use and was only released to obtain developer feedback.

Contact Information

Please send comments and suggestions for this website to:
Stanley Mitchell (stanm@genapps.net)