Any reference system is not a physical substance but a conventional artifact. The reason we need reference systems is that they are just convenient in exchanging the observational data and one's discoveries and opinions, which are starting points in doing science.
In this sense, the most important character of the reference system is that it is widely accepted and is related clearly with the other existing (existed?) references. Of course, in addition, it is hopeful to represent the actual phenomenon precisely. If the first point is respected, what we should do in the days of advanced electronic/computational environment is to thrust a movement toward the standardization.
We remark that the standardization never means the exclusion of other points of view. Rather it should be understood as only a scale which enables us to express observation/theoretical quantities in a concise manner.
As examples, we illustrate the present status of astronomical references; time, spacial reference frame, constants, standard procedures, and so on. Also, we introduce some activities within IAU, IERS, and IAG toward this goal.