FS                           Field Separator

    Value of input field separator.  Default value == /[\s\t\n]/; If FS set
    to  a  string  longer  than  a  single  character,  then  the string is
    interpreted as a regular expression.  This behavior is consistent  with
    the use of the RS variable.  Thus, the following two assignments of  FS
    are equivalent:

    FS = "[(){}[\\]<>]";
    FS = /[(){}[\]<>]/;

    When FS  is set  to a  single character  other than  a blank, then that
    single character is interpreted as the  field separator.  If FS is  set
    equal to a string  consisting of only a  single blank, " ",  then FS is
    set equal to the default value.

    FS may also be set on  the  command line  invoking QTAwk with  the '-F'
    option