HRM is a staff function but a line responsibility, comment.

Staff function is the position created to assist and enable the working of line functions. Staff functions include human resources, maintenance, legal, accounting and, public relations. Staff function involves assisting the line function with specialist advisory and expertise such as research, training, etc., to meet the business objectives.

Line responsibility is the daily operations of a business that directly fetch revenue. It involves the primary activities such as manufacturing, selling, purchasing, etc., which are required to meet the business objectives. Operations, marketing, and sales are examples of line functions.