Evaluate possibilities to express "default value type" of an SDC

We use the GDC 'scalar value specification' to quantify simple qualities or behavioural material properties ( mass = 1g, Rp02 = 100 MPa). What means do we have to specify default (or typical) quantity types in the definition/annotation/... of the SDCs?

The task is to evaluate different possibilites and present them for discussion.