This is kind of a follow up to the Aegon reforms question and I apologize if it is a bit long or boring. Do we have any information (or do you have any guesses) on how towns, cities and municipalities overall are originated and administered? Burghers were generally a separate class from manoral peasant IIRC and had unique privileges as well (though I may be wrong). Most municipalities seem to predate the Targs though so it seems a little unclear how is overseeing here. Additionally do you think

status hierarchy varies at all by region? I seem to recall from the Defiance of Duskendale section of WOIAF that Lord Darklyn was partially inspired by the fact that the Dornish lords retained their ability to autonomously administer cities (which is odd because they apparently don’t have any!). I completely understand if you want to correct me somewhere or if you think GRRM has not really developed this part of the worldbuilding.

One correction: Darklyn was primarily inspired by the Essosi paradigm (where you have full city-states), not the Dornish paradigm: “It was Lord Denys’s desire to win a charter for Duskendale that would give it more autonomy from the crown, much as had been done for Dorne many years before, that began the trouble. This did not seem to him such a vast demand; such charters were common across the narrow sea, as Lady Serala most certainly had told him.” (WOIAF, Aerys II)

The answer is we don’t know much. We know that city charters exist, we know they involve autonomy from the crown on some matters, notably “port fees and tariffs,” and that they require royal approval in the Crownlands and used to as well in the Riverlands when they were independent.

One thing we can say is that the most expansive form of rights, where cities were completely self-governing communes answerable to no one but the king, doesn’t exist in Westeros. White Harbor is ruled by the Manderlys, Oldtown by the Hightowers, Lannisport by the Lannisters, Gulltown by the Graftons.

From the little we know, city charters seem to be largely focused on taxation and other economic regulations – city charters allow cities to set their own port fees and tariff rates to some extent, allowing them to more effectively compete for trade. I say to some extent, because we know that Tywin and Aerys II fought over tariff rates and port fees at Oldtown, Lannisport, and King’s Landing, so it’s clearly not full autonomy. 

Based on historical parallels and the fact that city charters are expected to lead to expansion, my guess is that the main things that Westerosi charters involve are: 

• the right to hold markets and fairs and regulate them.
• the right to establish public warehouses where goods can be stored.
• the staple right, which means foreign merchants have to unload their goods in your town and exhibit them for sale there for a given period before moving on. 
• some sort of autonomy or revenue-sharing on port fees, tariffs, and other taxes on commerce.