anchor.diff:    ;
   
   row :
  -     element_list element_separator_list?
  +     quiet_element_separator_list element_list quiet_element_separator_list
     ;
   
   row_separator_list :
  -     row_separator (element_separator_list? row_separator)*
  +     row_separator (quiet_element_separator_list row_separator)*
     ;
   
   row_separator :
  
positive.code:   |  SEMICOLON
    ;
  
  element_list :
       element (element_separator_list element)*
    ;
  
negative.code:   ;
  
  matrix :
       lsquare optional_row_list rsquare
    ;
  
  cell_array :
       lcurly optional_row_list rcurly
    ;
  
  optional_row_list :
       quiet_row_separator_list row_list quiet_row_separator_list
    |  quiet_row_separator_list
    ;
  
  row_list :
  