is used to determine the mean of the cell parameters obtained from processing several data sets from the same crystal form. Cellparm expects the input data to reside in the file CELLPARM.INP and reports the mean of the cell parameters in file CELLPARM.LP. Typically, the mean cell parameters are used for input to XSCALE.
The refined cell parameters of each data set are reported in the file CORRECT.LP and also appear in the output file XDS_ASCII.HKL. The reliability of each set of cell parameters is indicated by the parameter WEIGHT=, which is typically the number of reflections used for refinement in the CORRECT step.

Example for CELLPARM.INP

! Characters in a line to the right of an exclamation mark are comment
! Each accepted input line (up to 20) consists of
! UNIT_CELL_CONSTANTS= a b c alpha beta gamma  WEIGHT=number
! Usually, WEIGHT= is the number of reflections used in the refinement
! of the cell constants in the GLOREF step. If omitted, WEIGHT=1.0.

!from mb_high/xds/GLOREF.LP
UNIT_CELL_CONSTANTS=64.585 30.911 34.886 90.0 105.822 90.0 WEIGHT=284516

!from mb_med/xds/GLOREF.LP
UNIT_CELL_CONSTANTS=64.584 30.932 34.879 90.0 105.832 90.0 WEIGHT=32106

!from mb_low/xds/GLOREF.LP
UNIT_CELL_CONSTANTS=64.658 30.972 34.918 90.0 105.823 90.0 WEIGHT=1966

Determines the weighted mean of the cell parameters as obtained from a high resolution, medium resolution, and low resolution data set from the same crystal.