Of course an id MUST start with a letter so all these examples using numbers are completely invalid.
Confused with DOM’s ID property and City ID?
Good point, forgot about that.
This does beg the question, why do you even need to pass the ID? A name/value pair should be enough.
The easies thing, of course, is to simply include it in the value. If the value was “Moscow”, you can turn it into “Moscow_346215” and then use PHP to split that into the city name and the ID.