The Int. check box means integrated logon for a user which means that the user will be linked to a user account in Windows. If you check this box you can, in a dialog window, enter a user account from Windows on the computer or from the domain in the Active Directory (AD). The selected user account will then be displayed to the right under Windows user.
Integrated logon means that the authentication of the user is not made against the user account in MONITOR, but against the user account in Window. Then it is not possible to enter a password for the user in this procedure.
By using the function File | Change company... or by double-clicking on the user name, on the status bar at the bottom right corner, you can logon as another user in MONITOR. However, during integrated logon you cannot logon as another user since the user is linked to the user account in Windows.