| DRAFT DICTIONARY CBF/imgCIF Extensions Dictionary | Draft version 1.5 for comment | 
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Definition:
       The value of _diffrn_data_frame.center_fast is
              the fast index axis beam center position relative to the detector
              element face in the units specified in the data item
              '_diffrn_data_frame.center_units' along the fast
              axis of the detector from the center of the first pixel to
              the point at which the Z-axis (which should be colinear with the
              beam) intersects the face of the detector, if in fact is does.
              At the time of the measurement the current setting of detector
              positioner given frame are used.
              It is important to note that for measurements in millimetres,
              the sense of the axis is used, rather than the sign of the
              pixel-to-pixel increments.
Type: float
Mandatory item: no
Category: diffrn_data_frame
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