# Methods for creating a datum coordinate system

 When you choose CSYS from the Create Datum dialog box, the Method list displays the methods for creating a datum coordinate system. Datum coordinates systems are used throughout Abaqus/CAE; for example, to define material orientations and to define connector orientations. To help you keep track of your datum coordinate systems, you can name the systems when you create them, and the name appears alongside their entry in the Model Tree.
 Related Topics Creating datum planes Controlling datum display

The following methods are available:

3 points

Define a rectangular, cylindrical, or spherical coordinate system by selecting the origin and, optionally, two additional points. In the case of a rectangular system, the second point defines the X-axis, and the XY plane passes through the second and third points, as shown in Figure 1. This is the most versatile tool for creating a datum coordinate system, and you should use it when possible. For detailed instructions, see Creating a datum coordinate system defined by three points.

Figure 1. Positioning a rectangular datum coordinate system by selecting the origin and two points.

Offset from CSYS

Select a coordinate system; and provide the location of the rectangular, cylindrical, or spherical datum coordinate system by specifying an offset, as shown by the example involving a rectangular system in Figure 2. You can specify the offset by entering a value or by selecting a point. For detailed instructions, see Creating a datum coordinate system at an offset from another coordinate system.

Figure 2. Positioning a rectangular datum coordinate system by offsetting from another coordinate system.

2 lines

Select two edges that define the rectangular, cylindrical, or spherical coordinate system. In the case of a rectangular system, the first edge defines the X-axis and the XY plane passes through the second edge, as shown in Figure 3. For detailed instructions, see Creating a datum coordinate system defined by two lines.

Figure 3. Positioning a rectangular datum coordinate system by selecting two edges.