FASTI, or Dies Fasti, likewise denoted court days. The word fasti fastorum is formed from the verb fari to speak, because during those days the courts were opened, causes might be heard, and the prator was allowed fari, to pronounce the three words, do, dico, addico. The days in which this was prohibited were called nefasti. Hence Ovid says,
Ille ne fastus erit, per quem tria verba silentur,
Fastus erit, per quem lege licebit agi.
The dies fasti were noted in the calendar by the letter F; but it is to be observed that there were some days ex parte fasti, partly fasti, partly nefasti, in which justice might be distributed at certain times of the day, and not at others. These days were called intercisi, and were marked in the calendar by the letters F. P. fasto primo, in which justice might be demanded during the first part of that day.