Assuming that we have the absolute parallaxes and homogeneous set of proper motions for a large number of stars as described by the previous speakers - how should we use them in studies of galactic structure and dynamics?

Concerning the parallaxes I will be very brief - the subject has already been discussed by Dr. Pagel. Clearly, the main importance of the absolute parallaxes obtained is in the calibration of photometric or spectrophotometric absolute magnitude scales. For a sufficient number of stars observed in the Hyades cluster at a distance of 50 pc and in the Scorpius-Centaurus association the systematic error, which lies at the bottom of all subsequent calibration of distance indicators, may be reduced to the same order as the accuracy of photometric measurements.