The following image shows a simplified diagram of the HymIS relational database. In the center of the database are the tables that contains the name combinations and the references. The higher taxonomy of the name combinations is structured in several tables, but not shown in this diagram. The table combinations contains every name combination only once and in the same table the connection to the basionym is stored.
The relation from a name combination to a valid species combination is shown in the table relations. This is always in dependence to a reference. Each reference having taxonomic information may be treated as a taxonomic concept and two or more references (e.g. five publications of one taxonomic concept) may be added to one single taxonomic concept. The tables are not included in the simplified database model.
Each database entry in the tables categories, types, distribution and pictures (some additional tables are not listed in the simplified database model) belongs to a name combination and to one reference. This is the basis of a potential taxon model, but not implemented in the HymIS database. The advantage that additional information, like distribution, is added to the name combination and not to a valid taxon is that this information may belong in different taxonomic concepts to different valid species. The interpretation if one name combination belongs to a synonym, to a valid species or even is a "nomen nudum", is not done on the level of name combination but on the level of taxonomic concepts. So each name combination is unique in the database. Also the rank or subgenus is not part of the name combination. This information is treated as an interpretation of the author(s) of a publication and therefor part of the taxonomic concept. If the rank and/or subgenus would be part of the name combination, the table of the combinations would increase manyfold, because one author treats a taxon as subspecies another one as variety and another one as form. If this taxon is mentioned in the literature in three different genera, the database would not have only one entry, but suddenly 16 entries. Don't forget that authors often don't specify which rank a taxon has or to which subgenus it belongs to.