For retrieving all contact lists of an account. The json payload returned for that call will always have the General Interest list, or whatever it may have been renamed to, in the first index of its results array ... I assume? Will a newly created list occupying a sequentially greater index have a list id number generated to be greater than the previous' list's id number? I am just trying to head off having to store list id numbers if the General Interest list will always occupy the first index in the results array.
The list ID value differs in how it is generated depending on if a customer is on our newer or older CRM technology. In the older CRM system, IDs were sequential and the responses were returned in ascending order. In the new CRM technology, it is a UUID that is generated from a variety of information and no assumptions should be made about ordering for new IDs.
With all that said, there is no guarantee that an account will have a General Interest list. It can be deleted, renamed, a new list with the same name could be created that would have a completely different ID. We do not recommend assuming that any specific list has a place in the payloads and that you do store the correct list ID that the API should be using in the updates or you could get unexpected behavior.