15.72.5  DIGITS 

DIGITS=n  selects  the  number  of  significant  figures  to reproduce for
lexicals.  If n is omitted it is assumed to be 4.  You may  also  set  the
number of digits with the SET DIGITS command.

                                  example
     TD:TITLE TOP 'Mean=',DIGITS=6,T_MEAN,' err=',DIGITS=2,T_EMEAN
The top title will be the mean and error for the data.