Customize menu > Preferences > Preferences Settings dialog > GCS panel > Global Coordinate System group > Define > Define
The Define Global Coordinate System dialog enables you to define a new coordinate system. Using this dialog requires advanced mapping knowledge.
Code—Specifies a code. The code must be unique within a category and across all coordinate systems, must comprise of 23 characters or less, and must not contain spaces. Only the following characters are valid: A-Z (upper or lower case), 0-9, dash, and underscore.
Units—Specifies the units to use in the coordinate system.
Description—Specifies a description. This description, not the code, appears in all list boxes, so be sure it is specific and descriptive.
Geodetic—Specifies that the coordinate system is geodetic and is based on datum.
Datum—Specifies the datum currently selected from the geodetic coordinate system.
Select—Displays the Select Datum dialog, where you can select a datum for the coordinate system.
Define—Displays the Datum Manager dialog, where you can create a new datum or modify an existing one.
Non-geodetic—Specifies that the coordinate system is non-geodetic and is based only on an ellipsoid.
Select—Displays the Select Ellipsoid dialog, where you can select a datum for the coordinate system.
Define—Displays the Ellipsoid Manager dialog, where you can create a new ellipsoid or modify an existing one.
Projection—Specifies the projection used for the coordinate system. The most commonly used projections are Transverse Mercator (for regions that are longer than they are wide) and Lambert Conformal Conic (for regions that are wider than they are long).
Select Northing or Easting to specify the number of linear units to add to either Y or X coordinates.
Northing—Specifies the number of linear units to add to all Y coordinates. If you chose an origin latitude that is south of the mapped area, this number is zero.
Easting—Specifies the number of linear units to add to all X coordinates.
Displays the parameters that you can set for the projection currently selected in the Projection list. The contents of this group changes dynamically as you select a different projection.
OK—Closes the dialog and saves any changes you’ve made.
Cancel—Closes the dialog without saving any changes you have made.