FUNCTION FXBISOPEN,UNIT
;
@fxbintable
        ON_ERROR, 2
;
;  Check the number of parameters.
;
        IF N_PARAMS() NE 1 THEN MESSAGE,'Syntax:  Result = FXBISOPEN(UNIT)'
;
;  If UNIT is undefined, then return False.
;
        IF N_ELEMENTS(UNIT) EQ 0 THEN RETURN, 0
;
;  Check the validity of UNIT.
;
        IF N_ELEMENTS(UNIT) GT 1 THEN MESSAGE,'UNIT must be a scalar'
        SZ = SIZE(UNIT)
        IF SZ[SZ[0]+1] GT 3 THEN MESSAGE,'UNIT must be an integer'
;
;  Get the state associated with UNIT.
;
        ILUN = FXBFINDLUN(UNIT)
        RETURN, STATE[ILUN] EQ 1
;
        END