Hi,
As I told you, in one shot, I don't thing it's feasible. Of course, it depends on how your database is written. You told me you have 350 repositories, and your database is an excel file. So maybe a routine could do the trick.
Then numbering schema, should be : RNL001, RNL002, etc..
R is for repository
NL, international code for Netherlands
xxx, digits to be incremanted
I asked Frederic to split the repositories gedcom file, to create country based repos files.
My two cents. Francois