Computer log

A computer log is a diary or archive of events, in this case generated by a computer system or systems. In the late- 23rd century, Federation starships were equipped with a "black box" that stored computer logs. The logs could be used in criminal investigations or to determine the cause of a lost ship. Computer logs were for official purposes only and were available to authorities only under specific legal circumstances or court-order. 

After Dukat and Kira Nerys captured a Klingon Bird-of-Prey in 2372, they found that the computer logs contained extremely valuable status reports from Klingon starships and outposts throughout the Cardassian Union.