2.41                      *******************
                                  * HNDCHK WRITE-UP *
                                  *******************


           HNDCHK is an interactive program to examine electron density
        values at specified locations within a map, usually for the
        purpose of determining the absolute configuration (hand). The
        program prompts for the parameter file, name of the map file and
        for the coordinates to be examined. The map file is read and the
        minimum and maximum density values along with sigma for the map
        are listed. Density values are then interpolated both at the
        specified coordinates and at places related to them by a centre 
        of symmetry, and are listed. In general, one would compute MIR,
        SIR etc phases, possibly solvent flattened, and then generate a
        Bijvoet difference Fourier map (with coefficients from MRGBDF)
        to be used with HNDCHK. One would then examine density values
        exactly at the input heavy atom positions used in the phasing.
        If the hand was correct, then large positive peaks should occur
        at the input sites, whereas if the hand was incorrect larger
        NEGATIVE peaks should occur at the TRUE heavy atom locations, i.e.
        at places related to the input (incorrect) positions by a centre
        of symmetry. 


                                   ***** FILES *****


        INPUT FILE  - Standard FSFOUR map, usually computed with the
                      Bijvoet difference Fourier option (MAPTYP=8)