2.42                      *******************
                                  * SLOEXT WRITE-UP *
                                  *******************


           SLOEXT is a program to control the rate and range of phase
        extension when extending phases to higher resolution by solvent
        flattening, negative density truncation and/or NC symmetry
        averaging. The program is automatically invoked by the "extnd.sh",
        "extnda.sh" and "extndavg.sh" scripts, and functions by updating the
        "extnd.d" or "extnda.d" files used by these scripts periodically
        during the extension process. The initial and final resolution
        cutoffs are specified by the user along with the number of map
        modification/phase combination cycles to be carried out at each
        resolution increment. The resolution is incremented in steps
        corresponding to roughly one reciprocal lattice point in the
        direction of the shortest reciprocal cell axis. If the initial and
        final resolutions are equal, then there is no gradual extension and
        only the number of cycles input is carried out. The controlling
        scripts assume that the input to MAPINV specifies indices out to the
        highest resolution to be encountered anywhere in the entire process.
        Likewise, the "extrfl.d" file prepared by MISSNG also should contain
        reflections out to the highest resolution. 


                            INPUT DATA  (UNIT 5)

        RECORD 1    PAMFILE      (free format)

                    PAMFILE = Input parameter file specifying cell and
                              symmetry information.



        RECORD 2    DINIT, DFIN, NC_INC       (free format)


                    DINIT  = Initial d spacing cutoff (starting value,
                             usually the resolution of the initial phase set)

                    DFIN   = Final d spacing cutoff (DFIN must be less than
                             or equal to DINIT. If DFIN = DINIT, then only
                             NC_INC cycles will be performed. Otherwise
                             for EACH RESOLUTION INCREMENT NC_INC cycles
                             will be performed).

                    NC_INC = Number of refinement cycles per resolution
                             increment (between 2 and 25).

        

        RECORD 3    CNTFIL       (free format)


                    CNTFIL = Name of file controlling phase extension. This
                             should be either "extnd.d" or "extnda.d" (UNIX
                             systems) or "extnd.dat" or "extnda.dat" (VMS
                             systems), depending on whether phase only or
                             phase plus amplitude extension is being done.
                             This file is referenced by the "extnd.sh",
                             "extnda.sh" and "extndavg.sh" scripts, or by
                             their VMS counterparts. The file is assumed to
                             exist and contains information as described in
                             the BNDRY write-up (option 3). It will be updated
                             periodically during the run.