Meh, I think that varies quite a lot. If the only functional difference between your duties and that of the the rest of your team is your paperwork, then you worked there.
The only time I specify whether something on my resume was a particular type of arrangement like contracting is if it would be weirdly short.
The only time I specify whether something on my resume was a particular type of arrangement like contracting is if it would be weirdly short.