As C9Trader Stratus is an application where each user has a unique login. You can see who is logged in and listening to each connection.
If there are only one or two other users on the connection, you will see their last names displayed on the button (Figure 1):
Figure 1 Connections
If there are more than two users, the connection will display the number of Subscribers (Figure 2):
Figure 2 Subscribers
To see the full list of subscribers and their status, right-click the connection button (Figure 3):
Figure 3 My Firm Subscribers