Projection - The two-dimensional representation of the three-dimensional space.

Coordinate System - a reference system for measurements defined by the projection

Geographic Coordinate System - measures locations in degrees - latitude and longitude. Since latitude and
longitude are angular measurements they are not suitable for measuring distances. The
major parameter of a Geographic Coordinate System is its datum

Projected Coordinate System - uses a projection to transform the latitude and longitude
to X and Y coordinates and makes the linear measurements more accurate. Each projected
coordinate system is based on a Geographic Coordinate System

Spatial Domain - the range and precision of coordinates that can be stored in a
feature dataset

Spatial Reference - contains information for the coordinate system and spatial domain
extent for a feature dataset

Projections of the data

Projected data - the data is explicitly projected in a Projected Coordinate System

Unprojected data - the data is in a Geographic Coordinate System

Data with unknown projection - the projection information is missing

ET GeoWizards works with data in any projection.

Notes:

All the wizards preserve the Spatial Reference of the input data source
unless an option is available and the user selects it. The assumption
is that if the user keeps a dataset in certain projection he has reasons for that,
and all the products of this data set must be in the same projection.

When a distance input is required ( Fuzzy tolerance, Dangling tolerance etc. )
best results will be achieved if the data is projected in a specific projection, because the
tolerance is compared directly with the data.

Although possible, it is not recommended to manipulate Unprojected data (data in a Geographic Coordinate System) for reasons
mentioned above.