Use reference geometry entities to control the parameterization of your profile. They are ignored in the creation of 3D shapes, but provide you more definition and control over the different features of your profile. For example, control the tangency point of an arc by inserting a reference line tangent to it and at a given angle, usually 0 or 90 deg, or the center of a rectangle.
Reference entities are auxiliary entities that help you better control the profile.
See the following illustrations and the notes related to the different reference numbers:
| 1. | By using a tangent, vertical, reference line, you can control the horizontal component of the profile. |
| 2. | The overall slot width can be established and dimensioned by two parallel and tangent reference lines. |
| 3. | To control the angle between two features on a profile, you can construct two reference lines to provide the angle. |