Re: New Orleans-Class
Could it be that the first digit of the five digit registries indicates the "birthplace" of that particular ship?
I just pulled Utopia Planitia Fleet Yards
and noticed that a couple of the ships listed there and whose registries began with "7" were also constructed there.
"The first duty of every Starfleet officer is to the truth" Jean-Luc Picard
"We can't solve problems by using the same kind of thinking we used when we created them." Albert Einstein