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

This package provides implementations for general positioning, coordinate reference systems (CRS), and coordinate transformations. Coordinates can have any number of dimensions. So this implementation can handle 2D and 3D coordinates, as well as 4D, 5D, etc.

This package provides a special implementation of {@linkplain org.geotools.referencing.NamedIdentifier identifier}, which is also a {@linkplain org.opengis.util.GenericName generic name}. By implementing those two interfaces, it is possible to use the same kind of object for specifying both the {@linkplain org.geotools.referencing.AbstractIdentifiedObject#getName main identifier} and the {@linkplain org.geotools.referencing.AbstractIdentifiedObject#getAlias aliases} of an {@linkplain org.geotools.referencing.AbstractIdentifiedObject identified object}.

All factory methods are capable to find an object using an unscoped (or local) name. However, in order to avoid potential conflict, it is recommanded to use scoped name when possible. For example even if both can work, prefer "EPSG:9624" instead of "9624" for the affine transform in order to avoid potential conflict with an other authority using the same code number.

### Command-line tools

A set of command lines tools is provided for performing queries. The tools are implemented in the `main` method of some key classes. The tools are:

{@link org.geotools.referencing.FactoryFinder#main FactoryFinder} | Lists registered factories found in the class path (not only Geotools implementations).
{@link org.geotools.referencing.operation.DefaultMathTransformFactory#main DefaultMathTransformFactory} | Lists registered math transforms found in the class path.
{@link org.geotools.referencing.CRS#main CRS} | Prints some informations about objects specified by their authority codes.
{@link org.geotools.referencing.Console Console} | A command-line tool for testing transformations.