Glue records for secondary NS

[Robert Moskowitz]

I just found out that I had old garbage in my rgistrar setup for my 
domain.  To wit, an NS server that has not been an NS server for years.  
And now that I use that host name for another usage on another address, 
it was giving lots of problems.  My bad, I should have caught this when 
I moved Registrars almost 2 years ago.

but...

glue records.

I have 3 secondaries run by other domains.  This was to give me some 
geo-diversity.  How do I create glue records for them?  My registrar 
only lets me create glue records within my domain (the web form 
pre-provides the domain part of the fqdn).  I can understand that in not 
allowing people to  populate fqdns on wrong addresses causing 
interesting problems (as I just figured out I have had).