{@linkplain org.geotools.referencing.crs.AbstractCRS Coordinate reference systems} implementation. An explanation for this package is provided in the {@linkplain org.opengis.referencing.crs OpenGIS® javadoc}. The remaining discussion on this page is specific to the Geotools implementation.

{@link org.geotools.referencing.crs.AbstractCRS} is the base class for all coordinate reference systems (CRS). CRS can have an arbitrary number of dimensions. Some are two-dimensional (e.g. {@link org.geotools.referencing.crs.DefaultGeographicCRS GeographicCRS} and {@link org.geotools.referencing.crs.DefaultProjectedCRS ProjectedCRS}), while some others are one-dimensional (e.g. {@link org.geotools.referencing.crs.DefaultVerticalCRS VerticalCRS} and {@link org.geotools.referencing.crs.DefaultTemporalCRS TemporalCRS}). Those simple coordinate systems can be used as building blocks for more complex coordinate reference systems. For example, it is possible to construct a three-dimensional CRS with (latitude, longitude, time) with an aggregation of {@link org.geotools.referencing.crs.DefaultGeographicCRS GeographicCRS} and {@link org.geotools.referencing.crs.DefaultTemporalCRS TemporalCRS}. Such aggregations are built with {@link org.geotools.referencing.crs.DefaultCompoundCRS CompoundCRS}.