not in the databases is floating around:

route-views.oregon-ix.net>show ip bgp
BGP routing table entry for, version 12484641
Paths: (43 available, best #41)
  Advertised to non peer-group peers:
  4513 13646 5696 568, (aggregated by 568 from (
      Origin IGP, metric 7602, localpref 100, valid, external, atomic-aggregate

[snip, route-views has more than a page of entries for it]

However, it doesn't apprar to be registered:

% whois -h whois.arin.net
No match for "".

568 regisitered to disa.mil, and a number of longer prefixes
inside the /10 are registered to .mil addresses:

% whois -h whois.arin.net
Kadena Air Base (NET-KADENA-NET)
   Bldg 792, Kadena AB JA
   APO, AP 96368-5149

The question is, do they legitimately own the whole /10? If
so, why isn't it marked in the databases?

Says who ? - maybe you didn't check the right one ?

whois -h whois.radb.net

descr: DISA, DSAC
               P. O. Box 1605
               OH 43216-5002, USA
origin: AS568
member-of: RS-COMM_US_FED
mnt-by: MAINT-AS568
changed: nsfnet-admin@merit.edu 19940819
source: RADB

Hash: SHA1

radb is a routing database, has nothing to do with ownership of ip

- --
Matt Levine
@Home: matt@deliver3.com
@Work: matt@eldosales.com
ICQ : 17080004
PGP : http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x6C0D04CF
"The Trouble with doing anything right the first time is that nobody
appreciates how difficult it was."

Perhaps I should restate my complaint a bit. I think all three
of these stand on their own.

* If sub-bits of an allocation are in the ARIN database,
  I think the supernet should be in the ARIN database.

* ARIN seems to have a good many, if not all of the .MIL
  supernets, but doesn't have this one.

* Having .MIL say they have address space is not proof
  that they own the whole block, anymore than www.ufp.org saying
  I now own 20 class A's is proof that they are mine.

In any event, I'd just like network lookups to work in some sane
way, so when operators need to check something they can get accurate

My theory is that DISO-UNRRA were originally allocated through in the classful world - these are all in the ARIN DB under various military guises. When CIDR came along, it seems that someone must have decided that because was now available and part of a bigger block, it could be added to the announcement, etc...?

There are a total of four like this:

Network Origin AS Description 568 DISO-UNRRA 10455 Lucent Technologies 568 DISO-UNRRA 568 DISO-UNRRA

Just a theory - but the above 4 could do with the x.0.0.0/16 being put in ARIN's db, if the allocation can be proven...