Do they mean for a given CYA level? Some of us have a shock level of 12ppm, while others are in the mid-20's or higher. Does that mean each of us has a different "safety" threshold for when you can swim?
Similar topic...given a standard TF100-type kit, what other thresholds would cause one to not swim? Meaning, if you encountered "xyz" levels when testing, you could NOT swim until resolved. What about swimming while the water's cloudy with dead algae?
Always been curious about this.