Using your times, it means you can't get in line before 8:35, or after 4:25. There's also the common sense clause. Although I haven't had any problems with those shops, the common sense is you know what they mean, even if it's not stated clearly and, given that schedulers do migrate from company to company, that's not something to challenge as you'd get an undesired reputation.
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Have PV-500 & willing to travel.
"Answers are easy. It's asking the right questions which is hard." (The Fourth Doctor, The Face of Evil, 1977)
"Somedays you're the pigeon, somedays you're the statue.” J. Andrew Taylor
"I have never met a man so ignorant that I couldn't learn something from him." Galileo Galilei