For SSC (Secondary School Certificate) Part 1 and Part 2 Regular students they will ask you to enter "ENTER STUDENT NAME AND REGISTRATION NUMBER AS PER REGISTRATION CARD ".
For SSC (Secondary School Certificate) Part 1 and Part 2 Private students side than they tell you to mention "ENTER STUDENT NAME AND FATHER NAME AS PER ADMISSION FORM ".
After that you can easily download your roll no slip within no time. This is just for verification so your roll number slips wouldn't go n wrong hands.
Best of Luck all the students of FBISE (Federal Board Of Intermediate & Secondary Education) Islamabad. If you guys have any other query regarding educational exams, yo can ask us freely via comment box or Contact form, Stay Safe.