the Alexander Chronicle, BM 36304) mentions that "ki-di-nu was killed by the sword" on day 15 of probably the 5th month of that year, which has been dated as 14 August 330 BC, less than a year after Alexander the Great conquered Babylon. The following information is an excerpt of the overview of a century of scholarship in the sources referenced below. The meaning of tersitu is not known definitively. Already Franz Xaver Kugler proposed that the word can be interpreted here as "table"; in another context it seems to mean something like "tool", but in yet another it refers to a blue enamel paste. P. Schnabel, in a series of papers (1923–1927), interpreted the phrase as an assignment of authorship. He argued that Naburimannu developed the Babylonian System A of calculating Solar System ephemerides, and that later Kidinnu developed the Babylonian System B. A Greco-Roman tradition, mentioned above, attributes to Kidinnu the discovery that 251 synodic months equals 269 anomalistic months. This relationship is implicit in System B, and is therefore another reason to believe that Kidinnu was involved in developing the lunar theory of System B. However, the conclusion that Kidinnu is the main creator of System B is uncertain. Babylonian astronomers before Kidinnu's time apparently already knew the Saros cycle (old eclipse observations were collected in tables organised according to the Saros cycle since the late 5th century BC) and the Metonic cycle (the dates of the lunar calendar in the Saros tables follow a regular 19-year pattern of embolismic months at least since 498 BC); both cycles are also used in System B. Schnabel computed specific years (first 314 BC and later 379 BC) for the origin of the System B lunar theory, but Franz Xaver Kugler and Otto E. Neugebauer later disproved Schnabel's calculations. Schnabel also asserted that Kidinnu discovered precession when distinguishing between sidereal and tropical years; Neugebauer contested this and current scholarship considers this conclusion to be unfounded. The lunation length used in System B has also been attributed to Kidinnu. It is 29 days + 191 time degrees + 1/72 of a time degree ("barley corn") = 29d 31:50:8:20 (sexagesimal) = 29d + 12h + 793/1080h (Hebrew helek) = 29.53059414...d. Being a rounded value in the archaic unit of "barley corns" it may be even more ancient. In any case, it is very accurate, within about ⅓ of a second per month.