A proposal by G.Thorud 27 Nov 2011.
See file link below.
Many of the most used US programs have to some extent implemented support for the citation style guide "Evidence Explained" (EE). In most cases the programs have parameterized the implementations allowing fields holding the information rendered in citations (Citation Elements, CEs) to be defined in a database for each Master Source Type. There are also Templates that control the output in citations in reports. At least one program exports these CEs in GEDCOM files, in a non-standard way, but other programs cannot read them. In general, it is currently not possible to exchange citation data according to EE between the major US programs using GEDCOM.
There has been much discussion on the wiki pro and con Evidence Explained. I see no reason to repeat these discussions here. No matter our opinion, EE support in programs will not go away, users will continue to record data according to EE, and there is a need to exchange these data between programs. At the same time there is a need to develop guides with definitions of Master Source Types for other countries, best done by users in those countries. Some of these guides should preferably contain more generic Master Source Types and Citation Elements than in EE, something along the lines that has been envisioned by those criticizing EE. It is also desirable to be able to import data from various databases on the Internet holding meta-data about sources, databases that are in many cases not designed for genealogy – this may also create a need for sets of Master Source Types supporting these data. All of the guides will evolve over time. Genealogy programs must therefore be able to handle and exchange data adhering to several guides, and it is preferable that source data can be converted from one guide to another making citation output consistent.
Since there will be many guides, the best solution is to allow programs to exchange definitions of the Master Source Types, Citation Elements and Templates, thus easing development, distribution and reducing duplication of work.
There is also a need to support exchange of citation data between users in different countries, often speaking different languages. It must therefore be possible to exchange translated definitions so that the receiver can understand the data, and can render the citations using her/his own language and cultural conventions, possibly in a different style – to the extent possible without very complex solutions.
It should also be possible to extract source and citation data from the more complex sets of Master Source Types, which can be transferred in the few fields that current GEDCOM defines, thus providing backwards compatibility – to the extent possible.
The suggested data model describes data structures that try to satisfy all these needs, and it tries to create a platform that will satisfy both those who supports EE and those who do not. Continuing to discuss pro and con EE will not bring us forward.
The data model is independent of the method used to transfer the data. I hope we can have a discussions split into several topics rather than one big discussion. One possible realization of the model is to specify an extension to current GEDCOM to hold these data.
The model is not finished in every detail, and there are some outstanding issues, but it should provide sufficient detail for discussions.
The document can be downloaded here
Sources and Citation data model DRAFT v 0.4 27nov2011.pdf