Originally Posted by Sabir Basheer

Those 8 series are due to 8 centers of written exams in alphabetical order i.e. Gilgit, Islamabad, Karachi, Lahore, Multan, Peshawer, Quetta and Sukkhar. Every center has separate series of candidates and the candidates' roll numbers are in alphabetical order of names in every series. For example the Gilgit center candidates start from 1 and end well below 1000 but upto 1000 roll numbers have been reserved for them. Above 1000 starts Islamabad series from candidate with name starting by 'A' and so on.
I hope it is well clear now.

Regards!