To Create a Global Dimension
1. Click > 
Dimension. The Select Reference dialog box opens.
Dimension. The Select Reference dialog box opens.2. Select a type of reference for dimension placement:
◦ 
—Select a reference to dimension.
—Select a reference to dimension.◦ 
—Select the tangent to an arc or circle to dimension.
—Select the tangent to an arc or circle to dimension.◦ 
—Select the midpoint of an edge or entity to dimension.
—Select the midpoint of an edge or entity to dimension.◦ 
—Select an intersection defined by 2 objects.
—Select an intersection defined by 2 objects.◦ 
—Select 2 points. Click the arrow to create a horizontal dimension 
or a vertical dimension 
between 2 points.
—Select 2 points. Click the arrow to create a horizontal dimension or a vertical dimension between 2 points.3. Enter a symbolic name for the global dimension.
4. Enter a numeric value for the dimension. The dimension is displayed with its symbolic name.
5. Middle-click to complete the dimension.