@Paul ********
I'm not going to remove this comment so we can all learn.
> but my understanding is if the Cat B visa is awarded because of and linked to a work permit,
A Non-B is a full page sticker (usually) that is issued BEFORE the extension of stay is granted. A Non-B Visa can not be cancelled.
>as soon as that job is finished/terminated then your visa only has 7 days validity after that.
IF a person is on a Non-B visa, it can not be cancelled and a person can stay the entire 90 days, up to the "admitted to" stamp.
IF a person is on an extension of stay based on employment, and it's cancelled, a person has until 11:59PM THE SAME DAY to leave Thailand. If they apply for another extension of stay that they don't qualify for, it will be rejected and they will have 7 days to leave the country.