2.29                      *******************
                                  * TRNMSK WRITE-UP *
                                  *******************
        
            TRNMSK is a program to transform a mask file constructed in a 
        "skewed" cell back to its conventional cell. In certain situations 
        (when the noncrystallographic symmetry is purely rotational), it is 
        highly advantageous to trace out the mask (via MAPVIEW) in terms of a 
        cell "skewed" such that the new b axis corresponds to the 
        noncrystallographic symmetry axis direction. In that case it is 
        usually obvious where the NC symmetry breaks down, and the envelope 
        mask for averaging is readily obtained. However, skewing the map is 
        not necessary for the averaging cycles, thus it is desirable to 
        transform the "skewed" mask, once created, back to the original cell 
        for all subsequent calculations. TRNMSK accomplishes this. 
        
        
                       INPUT DATA (UNIT 5)
        
        CARD I       PAMFIL = Input file containing cell parameters and
                              symmetry, used only to get "running log" file
        
        
        
        CARD II      INPMAP       (free format)
        
                     INPMAP = Input map file (corresponds to region extracted
                                              from original map before it was
                                              "skewed")
        
        
                                                           
        CARD III     INPMSK       (free format)
        
                     INPMSK = Input mask file (skewed)
        
        
        
        CARD IV      OUTMSK       (free format)
        
                     OUTMSK = Output mask file (unskewed), covers same region
                              as INPMAP
        
        
        
        CARD V       PHI, PSI, OX, OY, OZ         (free format)
        
                   
                     PHI =
        
                     PSI =
                             Input spherical polar angles and origin as
                      OX =
                             originally input to SKEW
                      OY =
        
                      OZ =
                                                     
        
        
                                ******** FILES ********
        
        
           INPUT MAP - As described for SKEW 
        
        
           INPUT (AND OUTPUT) MASKS - As described for SKEW