In researching a potential trip in Pakistan on Wikivoyage I came across this term which is not well explained:
The visitor should be aware of the ever changing rules regarding sensitive areas and No Objection Certificates (NOCs), Note Verbals and other permissions and paperwork some in officialdom deem necessary for your to travel around the country. The most notorious NOC regulation is for foreigners to enter Kashmir, with the intention being so the security services can keep track (i.e. follow) foreigners to make sure they don't visit places they shouldn't. Outside Kashmir diplomats are the primary user of NOCs and theoretically the normal tourist should be exempt. However those in officialdom can view all foreigners with suspicion and demand an NOC when you step of a plane or out of a bus. NOCs need to be applied for through the Ministry of Interior, however if you are traveling on a non-diplomatic passport you should be fine - but its good to be aware of this nonetheless.
There is a Wikipedia article but it is very brief and not very well worded:
No Objection Certificate or popularly abbreviated as NOC is a type of legal certificate issued by any agency, organization, institute or in certain cases, an individual, that does not object to the covenants of the certificate. This certification is a requirement at most of the government-based departments predominantly from the Indian subcontinent..
Can somebody explain better than these sources what an NOC actually is? Is it a kind of permit?