Glossary

Geometry

The shape that is associated with a feature. In many GIS systems the a feature can only have a single geometry type, where the type is constrained to being the same for the entire dataset.

Dataset

A table containing features.

Empty

It is known that a geometry does not exist within the feature’s domaine. Normally only needed for attribute tables with multiple geometry columns.

Null

The geometry is unknown. It may or may not be empty depending on the dataset.

API

Application Programming Interface. Often a set of classes (objects) and sub-classes that can be instantiated in a selection of computer languages.