What is the ID in SypexCityGeo?

Question

PHP

I determine the city by my IP, I get the following structure:

[city] => Array
        (
            [id] => 520555
            [lat] => 56.32867
            [lon] => 44.00205
            [name_ru] => Нижний Новгород
            [name_en] => Nizhniy Novgorod
        )

What is an ID, what kind of directory is it? Internal number in sypex database? the first two digits indicate the region, and what kind of 555 is unclear. I studied the documentation, I did not find the answer there.

Answer 1

numbers are immediately chewed
on nothing except for the element ID in the source array