This controls creation, modification, and deletion of rows in the line-signal-timer table, with the system's default timer profile at index 1 permanently protected from being modified or deleted. This is the same immutability pattern seen in ccasRSRowStatus and ccasProfileRowStatus applied here specifically to line-signal timer sets, ensuring a known-good baseline of make/break/debounce timers always remains available regardless of what custom timer profiles an admin creates. An admin tuning debounce and glare timers for a noisy trunk would create a new row at index 3 rather than risk breaking the protected default profile at index 1.