List of resources for published genealogical data models. Each entry, below, can be linked directly by using a URL with a trailing 'fragment identifier' (e.g. https://github.com/fhiso/bibliography/blob/master/datamodels.md#gedcom). The identifier names are, by default, the lower-cased headings with spaces replaced with hyphens (e.g. #event-gedcom).
"DeadEnds Data Model", BetterGEDCOM wiki (http://bettergedcom.wikispaces.com/DeadEnds+Model)
"Other Documents", bartonstreet.com (http://www.bartonstreet.com/deadends/) -- Various documents for DeadEnds model and the LifeLines product.
"The DeadEnds Data Model", bartonstreet.com (http://bartonstreet.com/deadends/DeadEndsModel.3.pdf) -- Recent (Sep 2014) update by the author (Tom Wetmore) given that the other online documentation is now quite old.
"Event GEDCOM", BetterGEDCOM wiki (http://bettergedcom.wikispaces.com/Event+Gedcom)
"FSDN Model", BetterGEDCOM wiki (http://bettergedcom.wikispaces.com/FSDN+Model)
"GEDCOM", FamilySearch Developers (https://familysearch.org/developers/docs/gedcom/) -- V5.5 and V5.5.1 specifications
"Original GEDCOM Data Model", BetterGEDCOM wiki (http://bettergedcom.wikispaces.com/Original+GEDCOM+Data+Model, http://bettergedcom.wikispaces.com/HISTORY)
"FamilySearch GEDCOM Specifications", Modern Software Experience (http://www.tamurajones.net/FamilySearchGEDCOMSpecifications.xhtml) -- Older specification documents.
"GEDCOM X", gedcomx.org (http://www.gedcomx.org/Specifications.html) -- Specification.
"GedML Data Format", BetterGEDCOM wiki (http://bettergedcom.wikispaces.com/GedML+Data%C2%A0Format)
"Genealogical Data Model", NGS (http://www.ngsgenealogy.org/cs/GenTech_Projects) -- Specification.
"GenTech Data Model", BetterGEDCOM wiki (http://bettergedcom.wikispaces.com/GenTech+Data+Model)
"GenXML", BetterGEDCOM wiki (http://bettergedcom.wikispaces.com/GenXML)
"Gramps 4.1 Wiki Manual", Gramps project (https://gramps-project.org/wiki/index.php?title=Gramps_4.1_Wiki_Manual) -- User Manual.
NB: Majority of online material is for 4.0 rather than the latest 4.1.
"Using database API", Gramps Project (https://gramps-project.org/wiki/index.php?title=Using_database_API) -- Database API.
"RELAX NG schema", Gramps Project (http://gramps-project.org/xml/1.6.0/grampsxml.rng)
"Document Type Definition (DTD)", Gramps Project (http://gramps-project.org/xml/1.6.0/grampsxml.dtd)
"Dates", Gramps project (https://gramps-project.org/wiki/index.php?title=Dates) -- Date handling.
"GEPS 021: Additional Name Fields", Gramps Project (https://gramps-project.org/wiki/index.php?title=GEPS_021:_Additional_Name_Fields) -- Gramps Enhancement Proposal to add new fields to the name object so as to better store a person's name for several cultures.
"Hierarchical Place Structure", Gramps Project (https://gramps-project.org/wiki/index.php?title=Hierarchical_Place_Structure) -- Description of hierarchical approach to handling place entities.
"Gramps Data Model", BetterGEDCOM wiki (http://bettergedcom.wikispaces.com/GRAMPS+Data+Model)
"OpenGen Data Model", BetterGEDCOM wiki (http://bettergedcom.wikispaces.com/OpenGen+Data+Model)
"Mike's Model", BetterGEDCOM wiki (http://bettergedcom.wikispaces.com/Mike%27s+Model)
"STEMMA Project", Parallax View (http://www.parallaxview.co/familyhistorydata/) -- Specification and several case studies.