nmap db schema?

Greetings,

Is there a published nmap db schema available?

I'd like to start storing minimal information about scans in a relational db 
for queries over time (host up/down, ports, hostname, mac addresses, etc).

If this information isnt readily available, I'll see about trudging through the 
nmap XML schema to see if I can define a workable db schema for my own use.

Regards,

-off

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