Centerline: How to?

[Firmso]

Hi,
How to draw a line (center of model) in family so when you import it to a project, Revit would recognize it as a centerline you could place a dimension from?
Thanks

[aaronrumple]

Draw a ref plane and set its properties to orgin.

[dbaldacchino]

You should also use the "Center (Front/Back)" or "Center (Left/Right)" assignment (becomes a strong reference).