Report Criteria Modified Time (Ticket)

Report Criteria Modified Time (Ticket)

I am attempting to create a report that will tell me how many tickets my employees worked for a given timeframe. Worked being defined as researching, communicating or resolving the issue all of which are documented via ticket conversations and time entries.  Can you please tell me what Modified Time (Ticket) represents exactly?  I would assume it is looking at whether or not the ticket was modified in any manner such as an added conversation, a field change or change of status, but I'd like to be sure I am correct.

Thank you!