Model-Based Definition > Model-Based Definition > Creating Various Annotation Types > Dimension Properties > Driven Dimensions > Placing Dimensions Using the Select Reference Dialog Box
  
Placing Dimensions Using the Select Reference Dialog Box
The Select Reference dialog box allows you to select the point on the model to which you want to attach a driven or reference dimension. It contains the following commands:
• —Allows you to select an entity. The dimension is attached to the reference at the pick point.
• —Allows you to select a surface.
• —Allows you to select an entity or surface.
• —Allows you to select the center of an arc or circle. The dimension is attached to the center of an arc or circle.
• —Allows you to select a midpoint of an edge or entity. The dimension is attached to the midpoint of the selected entity.
• —Allows you to select an intersection defined by two objects. The dimension is attached to the closest intersection point of two selected entities.
• —Allows you select two points or vertices and draws an imaginary line between the selected points or vertices. The imaginary line can be used as a dimension reference.
• —Allows you to select a point or vertex and draws an imaginary horizontal line through the selected point or vertex. The imaginary line can be used as a dimension reference.
• —Allows you to select a point or vertex and draws an imaginary vertical line through the selected point or vertex. The imaginary line can be used as a dimension reference.
 
* You can change the attachment type in the middle of creating a dimension. For example, you can select one point as on entity (), then change to center () and select another point.