The track segment defined by the silicon detectors is extrapolated onto
the downstream plate of the last doublet.
The prediction resolution is 
in the non-bending plane and for unknown momentum larger in the bending plane.
The deviation due to magnetic deflection increases the scanning area to an extent
which is acceptable in terms of scanning time.
The knowledge of the impact point on the first special plate improves the precision of the prediction on the upstream member of the doublet. This allows an efficient search of the impact point on the upstream plate of the doublet.
The combination of the two points measured in the silicon detectors and the two points in the special emulsion plates gives already a sufficient estimate of the particle momentum to restrict the search area on the middle doublet. The points on the second doublet in turn improve the momentum resolution, thus allowing for a better precision on the most upstream doublet. The combination of the three doublets gives a resolution better than 10% for all tracks below 15 GeV/c, which can be further improved with the additional information from the silicon trackers and the wire chambers.
All tracks, which are found at the interaction point can be followed downstream to the three doublets, and can have their momentum measured. This is a very important feature for the kinemetical analysis of the events. It is expected that this system allows for high efficiency in the momentum reconstruction and makes it possible to install fewer or less performant wire chambers.