The DEC function returns  character-string  value  that  is  the
  decimal equivalent of the specified parameter.  The return value
  is compatible with all other string types.

  Syntax:

     DEC( x [[, length[[, digits]]]] )

  The parameter 'x' is the expression to be  converted.   The  DEC
  function  can  take  a  parameter  of any type except VARYING OF
  CHAR, conformant parameters, or schema types.  The DEC  function
  requires the size of 'x' to be less than or equal to the size of
  INTEGER64 (if supported), or less than or equal to the  size  of
  INTEGER32.

  Two optional  integer  parameters  specify  the  length  of  the
  resulting string and the minimum number of significant digits to
  be returned.  If you specify a length that is too short to  hold
  the  converted  value,  the resulting string is truncated on the
  left.  If you do not specify values for the optional parameters,
  a  default  length  and  a default minimum number of significant
  digits is used.

  If the size of 'x' is greater  than  32,  the  defaults  are  20
  characters  for  the  length  and  19 characters for the minimum
  number of digits.  Otherwise, the defaults are 11 characters for
  the  length  and 10 characters for the minimum number of digits.
  Because the default length is  1  greater  than  the  number  of
  significant digits, positive numbers will be preceded by a blank
  and negative numbers will be preceded by a minus sign.