(, variously or ), the 15thday of "full months" and the 13thday of hollow ones, one day earlier than the middle of each month. These are thought to reflect a prehistoric lunar calendar, with the kalends proclaimed after the sighting of the first sliver of the new crescent moon a day or two after the new moon, the nones occurring on the day of the first-quarter moon, and the ides on the day of the full moon. The kalends of each month were sacred to Juno and the ides to Jupiter. The day before each was known as its eve (); the day after each () was considered particularly unlucky. The days of the month were expressed in early Latin using the ablative of time, denoting points in time, in the contracted form "the 6thDecember Kalends" (). In classical Latin, this use continued for the three principal days of the month but other days were idiomatically expressed in the accusative case, which usually expressed a duration of time, and took the form "6th day before the December Kalends" (). This anomaly may have followed the treatment of days in Greek, reflecting the increasing use of such date phrases as an absolute phrase able to function as the object of another preposition, or simply originated in a mistaken agreement of with the preposition once it moved to the beginning of the expression. In late Latin, this idiom was sometimes abandoned in favor of again using the ablative of time. The kalends were the day for payment of debts and the account books () kept for them gave English its word calendar. The public Roman calendars were the fasti, which designated the religious and legal character of each month's days. The Romans marked each day of such calendars with the letters: F (fastus, "permissible") on days when it was legal to initiate action in the courts of civil law (, "allowed days") C (comitialis) on fasti days during which the Roman people could hold assemblies () N (nefastus) on days when political and judicial activities were prohibited () NP (uncertain) on public holidays (feriae) QRCF (uncertain) on days when the "king" (rex sacrorum) could convene an assembly EN (, an archaic form of , "halved") on days when most political and religious activities were prohibited in the morning and evening due to sacrifices being prepared or offered but were acceptable for a