Isis, which calls itself Islamic State, has occupied the world's attention since it took over large swathes or Syrian and Iraqi territory this year, eventually declaring a new caliphate.
But precious little is known about the group, which has its own surprisingly slick PR machine, mainly because its record with journalists is tragically abysmal - militants sparked global revulsion by beheading US reporters James Foley and Stephen Sotloff, as well as killing many other local journalists.
Somehow, some journalists continue to report from the region, defying the incredible risks to document the group's many atrocities against not just journalists but Shia Muslims and religious and ethnic minorities.
According to the website Syria Deeply, journalists and activists still based in territory ruled by Isis have smuggled out official guidance issued by the jihadist group for journalists who continue to work in the areas it controls.
These 11 rules were reportedly issued in Deir Ezzor, eastern Syria.
1 Correspondents must swear allegiance to the Caliph [Abu Bakr] al-Baghdadi ... they are subjects of the Islamic State and, as subjects, they are obliged to swear loyalty to their imam.
2 Their work will be under the exclusive supervision of the Isis media offices.
3 Journalists can work directly with international news agencies (such as Reuters, AFP and AP), but they are to avoid all international and local satellite TV channels. They are forbidden to provide any exclusive material or have any contact (sound or image) with them in any capacity.
4 Journalists are forbidden to work in any way with the TV channels placed on the blacklist of channels that fight against Islamic countries (such as Al-Arabiya, Al Jazeera and Orient). Violators will be held accountable.
5 Journalists are allowed to cover events in the governorate with either written or still images without having to refer back to the Isis media office. All published pieces and photos must carry the journalist’s and photographer’s names.
6 Journalists are not allowed to publish any reportage (print or broadcast) without referring to the Isis media office first.
7 Journalists may have their own social media accounts and blogs to disseminate news and pictures. However, the Isis media office must have the addresses and name handles of these accounts and pages.
8 Journalists must abide by the regulations when taking photos within Isis territory and avoid filming locations or security events where taking pictures is prohibited.
9 Isis media offices will follow up on the work of local journalists within Isis territory and in the state media. Any violation of the rules in place will lead to suspending the journalist from his work, and he will be held accountable.
10 The rules are not final and are subject to change at any time depending on the circumstances and the degree of cooperation between journalists and their commitment to their brothers in the Isis media offices.
11 Journalists are given a license to practice their work after submitting a license request at the Isis media office.
i100.co.uk has not been able to independently verify that the decree is genuine but Isis expert Shiraz Maher said it was eminently feasible.
"It certainly seems possible," he said. "And it's written with the verbosity one would expect from Islamic State."
According to Syria Deeply, journalists that did not agree to these terms have left Isis territory, with some receiving incentives to return and others threats that their families would be crucified if they did not.
There are not thought to be any foreign journalists still working in Isis territory, so it would follow that these rules would only apply to Syrian and Iraqi reporters.