# Coordinate input

When you create entities in a drawing, they are located in relation to the underlying Cartesian coordinate system of the drawing. A drawing has a fixed coordinate system called the **World Coordinate System** (WCS).

You can also define arbitrary coordinate systems which are called **User Coordinate Systems** (UCS). They can be located anywhere in the WCS and oriented in any direction.

To specify points and distances using the keyboard, you can use the following formats:

- Cartesian coordinates: x,y,z
- Cylindrical coordinates: R<alpha,z
- Spherical coordinates: R<alpha<beta

## Relative coordinates

When you type the @-character in front of the entry, the coordinates are calculated with respect to the previous point. This technique is called **Relative Coordinates**.

When Dynamic Dimensions are active and you type a value in the **Length** field and add a comma (,), the content of the Length field is copied to the Command line and the @-character is placed in front automatically, which allows you to specify the next point using relative coordinates with respect to the previous point.

## Absolute coordinates

When a user-defined coordinate system is active, you can enter absolute coordinates (World coordinates) if you add an asterisk (*) in front. For example, *0,0 refers to the origin of the WCS (World Coordinate System).

## Working with Cartesian coordinates

- Type the x-, y- and z- coordinates separated by commas to enter the absolute Cartesian coordinates of a point.
- When the z-coordinate is omitted, the point is placed in the xy-plane (Z = 0).
- Type the @-character in front of the entry (@x,y) to specify the coordinates with respect to the previous point. This technique is called
**Relative Cartesian coordinates**.

## Working with cylindrical coordinates

A cylindrical coordinate system uses three perpendicular axes: the x-axis, the y-axis and the z-axis. All axes originate in the origin point of the coordinate system. The x-axis and the y-axis define a horizontal plane, while the x-axis and the z-axis respectively, the y-axis and the z-axis define vertical planes.

A point is defined using the following format: R<alpha, z.

- R = distance to the origin in the xy-plane.
- <alpha = the angle between R and the x-axis (positive angles are measured counter clockwise)
- z = the height above the xy-plane.
- When the z-coordinate is omitted, cylindrical coordinates are referred to as polar coordinates.
- Type the @-character in front of the entry to calculate the coordinates with respect to the previous point.

## Working with spherical coordinates

The spherical coordinate system uses three perpendicular axes: the x-axis, the y-axis and the z-axis. All axes originate in the origin point of the coordinate system. The x-axis and the y-axis define a horizontal plane, while the x-axis and the z-axis respectively, the y-axis and the z-axis define vertical planes.

A point is defined using the following format: R<alpha<beta

- R = distance from the origin
- <alpha = angle in the xy-plane (positive angles are measured counter clockwise)
- <beta = angle measured from the xy-plane (positive angles are measured counter clockwise, above the xy-plane)