The input symmetry data file used in calculating the Patterson Peaks was based on the Enraf-Nonius MolEN SPACE.ASC file. Information was added -- all origin choices, description of the origin, special positions, and data needed for table headings -- and corrections were made; the original file now constitutes only about 20% of the total file. A detailed description of the input symmetry data file follows:

  Columns  Format  Name     Description

 Record 1
   1-  4     I4    PAGE     Starting page number for output tables 
                             (useful when preparing tables a few at a 
                             time). 

 Record 2 
   1-  4     I4    NSPG     Space group number (e.g., "14" for P21/c) 
   5-  8     I4    SYSTEM   Crystal system 
                             1 = triclinic
                             2 = monoclinic
                             3 = orthorhombic
                             4 = tetragonal
                             5 = trigonal (if R, rhombohedral axes)
                             6 = hexagonal (if R, hexagonal axes)
                             8 = cubic
   9- 12     I4    NCENT    Centrosymmetry indication 
                             0 = no inversion center AT ORIGIN OF CELL
                             1 = inversion center AT ORIGIN OF CELL
  13- 15     3X    (blank) 
  16- 23     A8    SGNAM    Space group name (short form) 
  24         A1    KAXIS    Axis choice (e.g., "b" for b axis unique) 
  25- 26     I2    KCHOICE  Setting or origin choice (if applicable) 
  27- 31     5X    (blank) 
  32- 47     A16   SGNAMFUL Space group name (long form) 
  48         A1    SCH1     The three parts of the Schoenflies symbol 
  49- 50     A2    SCH2      for the space group (main, superscript, 
  51- 52     A2    SCH3      and subscript) LEFT JUSTIFIED
  53- 56     I4    NEQV     Number of general equivalent position 
                             records to follow for the general position
                             (do NOT include records for positions 
                             generated by lattice centering or by an 
                             inversion center AT ORIGIN OF CELL) 
  57- 60     I4    NORG     Number of origin description records (1-2) 

 Record 3
   1-  2     I2    IA(1)    Lattice centering code
                             0 = Primitive
                             1 = A-centered
                             2 = B-centered
                             3 = C-centered
                             4 = F-centered
                             5 = I-centered
                             6 = R-obverse
                             7 = Hexagonal
   3- 26     12I2  IA(i)    Extinction conditions (IA(2)-IA(13)) 

 Records 4 (total of NORG records) 
   1- 80     A80   ORIG     Description of unit cell origin in text 
                             form, using one to two records.   The 
                             back-slash character (\) indicates where 
                             a new line begins.

 Record 5
   1-  4     I4    SMULT    Site multiplicity
   5         1X    (blank)
   6         A1    WYCKLET  Wyckoff letter identifying position
   7         1X    (blank)
   8- 23     A16   SSYM     Site symmetry

 Records 6 (total of NEQV records)
   1- 45     15I3  IA       Matrix/vector form of equivalent positions 
                             (do NOT include records for positions 
                             generated by lattice centering or by an 
                             inversion center AT ORIGIN OF CELL)

 Record 7 (only if WYCKLET above is not "a") 
   1-  4     I4    SMULT    Site multiplicity
   5         1X    (blank)
   6         A1    WYCKLET  Wyckoff letter identifying position
   7         1X    (blank)
   8- 23     A16   SSYM     Site symmetry

 Records 8 (total of SMULT records -- see Record 7)
   1- 45     15I3  IA       Matrix/vector form of equivalent positions 
                             (note: for the special positions, include 
                             all positions except those generated by 
                             lattice centering)

     Repeat Record 7 and Records 8 as needed to 
     include ALL sets of special positions for
     this space group.   Then, begin again with 
     a Record 2 to start the next space group.

Example:

The entry in the input symmetry data file for space group #14, unique axis b, second cell choice (P21/n):

   67
   14   2   1   P21/n   b 2     P 1 21/n 1      C5 2h   2   1
  0 0 3 0 0 0 0 0 0 0 0 1 0
 at -1
    4 e 1
   0  0  1  0  0  0  0  0  1  0  0  0  0  0  1
   1  2 -1  0  0  1  2  0  1  0  1  2  0  0 -1
    2 d -1
   1  2  0  0  0  0  0  0  0  0  0  0  0  0  0
   0  0  0  0  0  1  2  0  0  0  1  2  0  0  0
    2 c -1
   1  2  0  0  0  0  0  0  0  0  1  2  0  0  0
   0  0  0  0  0  1  2  0  0  0  0  0  0  0  0
    2 b -1
   0  0  0  0  0  0  0  0  0  0  1  2  0  0  0
   1  2  0  0  0  1  2  0  0  0  0  0  0  0  0
    2 a -1
   0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
   1  2  0  0  0  1  2  0  0  0  1  2  0  0  0