(covers information from several alternate timelines)
A sensor log shows various data with their respective time indexes
A time index, or time code, identified the temporal coordinates of a piece of data in a data stream, a recording or a data clip.
In 2366, Geordi La Forge used the time index to replay audio transmissions of Data aboard a shuttle, which had exploded and apparently killed him. (TNG: "The Most Toys")
Late that year, the time index of a battle between the USS Enterprise-D and a Borg cube showed a slight power drop in the cube's systems after Data had begun to fluctuate the phaser resonance frequency. (TNG: "The Best of Both Worlds")
In 2367, La Forge used the time index of a recording of an away mission to Tarchannen III to search for audio and visual anomalies. (TNG: "Identity Crisis")
In 2368, Data employed the time index to replay the words of the Tamarian Dathon. (TNG: "Darmok")
Later that year, according to Captain Satelk, the time index of pictures taken by a satellite around Saturn showed Nova Squadron seven seconds after completing a Yeager loop. (TNG: "The First Duty")
In 2369, Data created a holoprogram where he physically killed a Borg drone. He repeatedly reset the time index of the program to increase the drone's strength. (TNG: "Descent")
In 2370, Keiko O'Brien noticed an anomaly in the data clip showing the death of her husband, which eventually led to the discovery that the clip was a forgery. The time index showed that it was afternoon and her husband was drinking coffee, which she believed was uncharacteristic for him. (DS9: "Armageddon Game")
In 2371, Odo used the time index of the USS Defiant's bridge security log to show a young Jem'Hadar his people. (DS9: "The Abandoned")
The same year, Lursa used the time index of the transmissions received from La Forge's visor to discover the Enterprise's shield frequency. (Star Trek Generations)
In 2372, Worf used the time index to replay a recording of the Antwerp Conference at low speed to show evidence of Changelings on Earth. (DS9: "Homefront")
In 2375, Harry Kim restarted the time index of a holoprogram, depicting USS Voyager using quantum slipstream drive, twenty-three times to not have the simulation end in Voyager's destruction. (VOY: "Timeless")
The same year, Captain Kathryn Janeway compiled a list of sensor readings at various time indexes to identify Borg signals. (VOY: "Dark Frontier")
In 2390 of an alternate timeline, the EMH discovered the exact Borg time index Seven of Nine's cybernetic systems were terminated. Kim then used a time index less than four minutes before that point to transmit a message into the past. (VOY: "Timeless")