I forget which nation from the far side of the Pacific featured this fun logo, when I went Googling for "r21" pics (that's shorthand for "reilly2001," you see).
So my Java classes can be the shortened: info.r21.package.class ...
and my XML Namespaces can use <xmlns:r21 http://reilly2001.info/whathaveyou>
Oughta work O.K.; not too likely nameclashes, even though I don't own r21.info.
Wm.