Autodesk 24000-000000-9860 - Revit Architecture - PC User Manual page 385

Example of reference lines
sketched as a polygon
When selected or highlighted during preselection, the associated planes display according to
the active view.
Example of reference line chain highlighted during pre-selection in a
3D view
To use reference lines and linear dimensions to control model geometry:
3 Align the face of a model element to the reference line and lock it.
4 Add a dimension line referring to the reference line and label it as an instance or type parameter.
For more information on dimensions, see
5 Flex the model by changing and applying a new value within the Family Types dialog.
Controlling Angular Dimensions with Reference Lines
The preferred method to control the angular dimensions of a family is to apply a labelled angular dimension
to a reference line. Unlike reference planes which have infinite extents, a reference line has a specific start
and end point which allows it to control the angular constraints within components such as a web truss or
a door with a instance door swing.
Dimensions on page 213.
General Rules for Geometry Creation | 347