What is PNIL:
A DAWN article on 20 Dec 2018 says
The Federal Investigation Agency (FIA) told the Senate Standing Committee on Human Rights on Wednesday that it had been preventing individuals from leaving the country on the basis of a self-designed Provisional National Identification List (PNIL) to bypass the lengthy process of putting such people on the Exit Control List (ECL).
“The procedure was designed after the Supreme Court directed the FIA to prevent serious offenders from travelling abroad,” FIA Director General Bashir Ahmed explained. The committee had demanded that both the Ministry of Interior and the FIA explain the functioning of the PNIL.
Source
Let us not forget, Shahbaz Sharif is the main accused in Model Town Killings, a serious crime.