Word for employees without management responsibilities

I'm looking for a noun or adjective noun combination that, as clearly as possible, explicitly identifies employees that don't have anyone reporting to them.

The closest existing question I could find was A word for people who work under a manager and it doesn't help me because people who fit that description are not precluded from having subordinates of their own.

Required example: We categorize employees as upper management when they report only to the board of directors. Middle management personnel report to another employee and also have employees reporting to them. [some noun or adjective noun combo] are employees that have no subordinates in the company.

There's rank and file:

the individuals who constitute the body of an organization, society, or nation as distinguished from the leaders.

the chosen few might have the opportunity for a trip in the space shuttle, but it will be a while before the rank and file are taking space trips.

_{from m-w.com}

A nonmanagement employee is:

Not a member of management

[I have to add this separately because I'm not allowed to comment on other's posts yet]

Staff: Where I've worked, 'staff' has been used to distinguish people on the company' payroll, from contractors and consultants, so it does not have anything to do with management responsibilities (apart from the fact that a consultant manager will not be in the company's own management hierarchy).