Overall architecture of the vegetation plot module.

1. Vegetation plots can be viewed as occurring at a locality.

2. A plot observation occurs at the locality. Plot databases contain site information and taxon co-occurrence data collected at the plot.

3. Plots in plot databases can be interpreted as representing communities (syntaxa) that exist in community classifications.

4. Plot observations/collections include observations/specimens of one or more taxa. These same organisms can be observed in multiple plots.

5. Organisms can be interpreted as representing biological taxa that exist in various classifications.

1. A research project can contain one or more plot observations. The project contains information that is in common among all the observations that belong to the project.

2. Plots can contain plots. Each subplot references its parent plot through a recursive foreign key to another plot.

3. A plot record contains or references information about attributes of the plot that will not change between temporally displaced observations of the plot.

4. An observation contains or references information about attributes that might differ between observation events.

5. A plot most have at least one observation and can have several observations, each of which references the parent (earlier) observation via a recursive foreign key to that observation.

6. An observation can be interpreted (by one or more parties) at one or more times as belonging to one or more particular types of vegetation. A vegetation type corresponds to a "community concept" in the community taxonomy module. Because vegetation can change, there is no necessary relationship between the interpretations at different observation events for a plot.

7. At each observation event, plant taxa are observed and their attributes are recorded.

8. Each plant taxon observed is interpreted as belonging to a particular plant concept in the plant taxonomy module. Taxa can be assigned various interpretations at various times by various parties.