Conf TL means a Confirmed Timeline Entry.
All the train details and updates that you see on our website are manual done by the members and the admins.
If the update is done...
more... by non-admin members, it is validated by the admins and approved accordingly after which the change starts to appear on the train details page..
All these updates are called Timeline Updates and whenever they are approved, it is known as a confirmed timeline update or a Conf TL.
Vivek