SUBROUTINE UNIT(STRING,SUBSTR)
      CHARACTER*28 STRING
      CHARACTER*3 SUBSTR
      DO 1400   I1=1,28
      IF( STRING(I1:I1) .EQ. '('   )   THEN
       DO 1200   I2=I1+1,I1+3
       IF( STRING(I2:I2) .EQ. ')'   )   GO TO 1300
 1200  CONTINUE
       I2=I2+1
 1300  CONTINUE
       IF(I2-I1 .EQ. 1)  THEN
        SUBSTR='   '
       ELSE
        SUBSTR=STRING(I1+1:I2-1)
       END IF
       RETURN
      END IF
 1400 CONTINUE
      RETURN
      END