RailFanning is our All-Rounder Glucose that gives us Instant Power in All Seasons - Kirti Solanki

try your self booking and canceling some confirm and GNWL ticket and you too will get experience.
Step 1 book one confirm ticket
Step 2 in same train book one Wait list ticket
Step 3 Now Cancel the confirm ticket ( remember to do this before chart Prepaartion and see what is your current waitlist number before cancelling your confirm ticket)
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4 immediately after cancelling your confirm ticket check your waitlist ticket it must have come down by 1 number.
In tatkal WL if some one cancel Tatkal confirm or Tatkal Wl ticket before chart preparation then only Tatkal Wl will move and rest as per the quota of Tatkal for each train (differ in each train) alloted for Tatkal WL will confirm.