Error code layout and definition

I’ve noticed that on some errors the description text and first 12 characters are the same.
But the last 6 characters are different. The HMS code pages don’t mention anything else the last six characters. And searching for those numbers doesn’t return anything.

Is there a document on how to research the last six characters.

There are a couple of pages you could check out, see below. Sometimes removing the dashes or underscores could help.

I reviewed the first page previously. Wasn’t aware of the second.
Neither page covers the last 6 characters.

Please provide the entire code.