Fed_tax_data says it was last updated by online user - what exactly does that mean?

On the fed_tax_data table, on the last_action field, what is the difference between 'O' - online user and ''W' - employee self service. 

So I just want to confirm, this means that the rows with a W, the employee entered themselves.  If the row has an O, it means someone ( most likely in payroll) entered it for them.

Please confirm my understanding.