Edit 11/09/2020: It’s occurred to me that the AVC numbers may conform to this as well, and it appears they do. (Albeit to the sample size of 1 because I don’t have access to anyone else’s AVC except my own)
Just noting down that NBNCo Location ID’s use the Verhoeff algorithm to generate their check digit, since nobody appears to have mentioned it in a Google-indexed, website to my knowledge.
Remember to strip out the LOC and leading zeroes of course.
Why? They were likely afraid of any chance of a manually entered LOCID having any transposition error causing unintentional porting…
Except, that still happens because customers aren’t entering raw location ids into their orders, but typing and clicking on probably outdated address searches that resolve to location ids.
From the Operations Manual:
Note that while their own example does not generate a correct check digit, ones in the wild conform to the above mentioned algorithm. (The last digit should be 4 in the example.)