The DM81LS97AJ is a bus driver/transceiver from National Semiconductor, designed for bidirectional data flow on a common bus line. It handles the drive and receive side of a parallel bus, which means it sits between a controller and a memory or peripheral bus where you need controlled impedance and enough current to drive multiple loads. Typical use is in older 8-bit or 16-bit microprocessor systems, industrial controllers, and telecom line cards that still run on 5 V logic.
If your assembly line is set up for lead-free reflow (260 °C peak), this part will not survive the profile without damage. It is a fit for military, aerospace, or legacy industrial builds that have a leaded-solder exemption or a dedicated line. For a standard commercial RoHS build, you will need to find a lead-free equivalent or get a waiver.