What is 'Track-at-Once'?
Track at Once is a writing mode that allows multiple sessions to be written to a disc. The written sessions contain complete "tracks" of information or audio.
Because the laser is turned off and on for every track, the recorder leaves a couple of blocks between tracks, called run-out and run-in blocks. In audio CDs these blocks are two second gaps of silence placed between each audio track. Recording the CD using the Disc-at-Once writing mode will eliminate the two second gap. Before using Disc-at-Once, verify that your CD-R/RW drive supports the option.