The soft limiter allows minor transient excursions up to 100.5% N1 to maintain 107% NR. Just after this excursion, the limiter will immediately begin reducing the N1 at a rate of 0.1% per second to 100%. This soft limiter logic is then reset and again becomes available once N1 goes to 99.9%.
Like you say, don't plan to use it, but it is a handy tool for unexpected events.
Pedro