1) dâdé (#); 2) dâdebon; 3) farâzbon
1) A single piece of information, as a fact, statistic, or code.
L. datum "given," neuter p.p. of dare "to give, offer," cf. Av. and O.Pers. dā- "to give, grant, yield," Av. dadāiti "he gives," Skt. dadáti "he gives," Gk. didomi "I give," PIE base *do- "to give."
Dâdé "given," p.p. of dâdan "to give,"
Mid.Pers. dâdan "to give," O.Pers./Av. dā- "to give, grant,
yield," akin to L. data, as above.
Fr.: donnée géodésique
The → zero point of elevation on Mars. It is the elevation at which the atmosphere pressure is 6.1 millibars, or 610 → Pascals. Atmosphere pressure has to be used because Mars has no ocean, and "sea level" cannot be used like on Earth. More formally, the datum is a fourth-order, fourth-degree surface of equal → gravitational potential (determined from the Viking orbiter spacecraft) such that the pressure of the atmosphere is 6.1 millibars (source: Lunar and Planetary Institute, USRA).