This Integer32, measured in lines, reports the current total number of lines in the file being scanned by the fscan agent. An admin tracks it alongside lengthrate to gauge how actively the monitored file is growing, which provides context for interpreting the per-pattern matches and total counters in the scanTable. For example, a length that has stopped increasing even though matches are still expected would indicate the source log has stalled rather than that matching patterns have simply stopped occurring.