New Covid restrictions went live at 18:00 on Friday, resulting in the closure of pubs and restaurants in the central belt until at least 25 October.
The one exception is for cafes which can open during the day.
A last-minute scramble for legal advice has seen businesses try to fit the definition.
Stephen McGowan is a licensing solicitor at TLT in Glasgow. He told BBC Scotland his phone was "red hot" with clients on Friday afternoon asking how they fitted into the definition.
He said: "The definition Nicola Sturgeon gave puts us in a better place than before with something to work with but it is still open to interpretation.
"There has been disappointment for thousands of businesses who thought they had the opportunity to stay open."
He added: "Some clients fit the definition or are close enough to it that I am comfortable with them opening and some I have had to say sorry, but I don't think you are near enough.
"I have had tears on the phone and it has been difficult listening to operators I have known for years."
He said the first minister specifically saying two key things is what shut down many of their hopes: anyone confused about whether they are a cafe or not should close while they seek clarification, and that the regulations are not intended to allow bars and restaurants to convert into cafes.
The big question is which businesses can remain open as cafes? The Scottish government definition is this:
"An establishment whose primary business activity, in the ordinary course of its business, is the sale of non-alcoholic drinks, snacks or light meals."
But Nicola Sturgeon said more about what it was not than what it was. She said restaurants and bars could not convert themselves into cafes in a bid to stay open.
She said the business may or may not have a licence to sell alcohol, but they must not sell it while they are open.
And she said if there is any doubt about whether a business is a cafe or not, it should have closed at 18:00 on Friday and remain closed while seeking clarification from the local authority.
Paul Waterson from the Scottish Licence Trade Association (SLTA) says the situation was no clearer than it was on Thursday.
He said: "There is one licence for all premises who sell alcohol and there is no differentiation between restaurants, pubs, bars and so on. This explanation has caused more questions than answers.
"When does a restaurant become a cafe? When does a pub become a restaurant? When does a bar become a pub? It's a ridiculous situation. "
And then to say the reason cafes can open is to allow social interaction between people when we are closed to stop social interaction beggars belief. People are asking us what a licensed cafe is."
Mr Waterson said he would not want to see owners breaking the rules, but said: "It is very difficult when businesses are in real trouble to get them to conform to situations.
"If your business is under threat you will do everything you can to save it.
"What are we going to tell these people whose businesses are ready to close and they won't get through the next two weeks?"
James Withers of trade body Scotland Food & Drink, said: "Many cafes, restaurants and eateries in central Scotland have spent Friday trying to work out if they have to close for 16 days.
"It has been a nightmare for them trying to interpret new regulations, coming out just hours before a potential closure, whilst they are trying to manage their staff rotas and the ordering or cancellation of supplies. I genuinely worry about the mental health impact of the last few days."
Tighter restrictions will also come into force in the rest of the country with licensed premises unable to serve alcohol indoors and operating limited opening hours.
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