 This file specifies which residues will be varied
 Column   2:  Chain                               
 Column   4-7:  sequential residue number         
 Column   9-12:  pdb residue number                
 Column  14-18: id  (described below)             
 Column  20-40: amino acids to be used            
                                                  
 NATAA  => use native amino acid                  
 ALLAA  => all amino acids                        
 NATRO  => native amino acid and rotamer          
 PIKAA  => select inividual amino acids           
 POLAR  => polar amino acids                      
 APOLA  => apolar amino acids                     
 NOTAA  => select all BUT the designated amino acids
 APOGR  => for all native apolar amino acids select only apolar amino acids
           as large or larger; native POLAR amino acids are not designed
 VARYB  => for DNA; only design positions within 6A of this base
 The following demo lines are in the proper format
 A    1    3 NATAA                                
 A    2    4 ALLAA                                
 A    3    5 NATAA                                
 B    4    1 PIKAA  DFLM                          
 B    5    2 PIKAA  HIL                           
 B    6    3 POLAR                                
 -------------------------------------------------
 start
 A    1    5 NATAA
 A    2    6 NATAA
 A    3    7 NATAA
 A    4    8 NATAA
 A    5    9 NATAA
 A    6   10 NATAA
 A    7   11 NATAA
 A    8   12 NATAA
 A    9   13 NATAA
 A   10   14 NATAA
 A   11   15 NATAA
 A   12   16 NATAA
 A   13   17 NATAA
 A   14   18 NATAA
 A   15   19 NATAA
 A   16   20 NATAA
 A   17   21 NATAA
 A   18   22 NATAA
 A   19   23 NATAA
 A   20   24 NATAA
 A   21   25 NATAA
 A   22   26 NATAA
 A   23   27 NATAA
 A   24   28 NATAA
 A   25   29 NATAA
 A   26   30 NATAA
 A   27   31 NATAA
 A   28   32 NATAA
 A   29   33 NATAA
 A   30   34 NATAA
