com/dictionary/blue-collar is: "of, relating to, or constituting the class of wage earners whose duties call for the wearing of work clothes or protective clothing" So then is a doctor or surgeon a blue-collar? No, definitely not. 'Blue collar' refers to people who are factory workers, auto mechanics, bus drivers, etc.
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CliveHi,Hi Clive,
Just a brief note about the phrase 'a salary man'. This term is not used in Western English-speaking countries.
Best wishes, Clive