XO - a Tier 1 or not?

[w3yni1 at gmail.com (Charles Mills)]

Trying to sort through the marketecture and salesman speak and get a
definitive answer.

I figure the NANOGers would be able to give me some input.

Is XO Communications a Tier 1 ISP?

I'd say no based on all research and googling that I've done but they
seem to meet some of the criteria (some != all and therefore not Tier
1).

Any help here?  Thanks as always.

Chuck