Bdi (both days included). A term found in charterparties and abbreviated as shown in communications between shipbrokers and their principals.
The term would be appropriate to limiting the meaning of dates in a clause specifying the earliest date and the latest date the ship can commence its performance of the charter. The earliest and the latest dates are found in the laycan clause, the date laydays should commence and the date by which the charterers can cancel the charier if the ship a not ready to perform.