You can create new reference dimensions, and you can convert existing dimensions to reference dimensions. Reference dimensions must have at least one section geometry entity.

The symbolic name for a reference dimension is rsd# REF, where # represents the dimension ID. You can refer to reference dimensions in Sketcher as sd# or as rsd#. Reference dimension names cannot be used as parameter names.

When you create a relation, you can use known and reference dimension on the right-hand side, however, carefully use the reference dimensions. Reference dimensions are dependent of the section geometry and require regeneration. Regeneration updates the section geometry, which updates the reference dimensions.