Reference dimensions often are the result of complex geometric manipulations. They could be used as the basis of the design of a future part. If I want to create a completely parametric part, as it stands, it is necessary to manually calculate the value of a reference dimension through very long equations. It would be much simpler to include a reference dimension (possibly called "R1", R2,... in the equation.

Using reference dimensions in equations runs the possibility of creating circular references so it would be necesary for Alibre to either check for this (likely a complicated process since it currently does not even check for renamed variables) or create a circular calculation setting that specifies the number of iterations allowed. Another option is to treat the reference dimension as a constant each time the equation is executed and leave it to the operator to run it multiple times as desired.