The GEDCOM 5.5 and 5.5.1 specifications describe in detail the text file format which is used to encode genealogical data as well as the higher level data structures of the lineage-linked form. Much is written about the interpretation of specific GEDCOM tags and variations in exported files from different genealogy applications. Here, the focus is on a class model of the GEDCOM lineage-linked form as defined in the specifications.

Drawing diagrams and documenting a model is tedious work, which is much helped by using a UML tool to generate an HTML report. This model was developed using Enterprise Architect from Sparx Systems. The current model is at version 0.6:

GEDCOM 5.5/5.5.1 Logical Data Model
(an HTML-frame based model browser)