Thanks - that's why I mentioned it... it seemed unusual. The note appears in the 7180 schematic checklist, section 3.6, where it reads (for the XTAL1 pin) "Outputs 1.8v to external crystal". And then under the 'crystal sources' notes in the same section, it talks about how the pin should be connected to "the 1.8v 28.63636MHz fundamental crystal." So I wasn't quite sure what to make of that.
I guess what I'm ultimately after is the drive level of the 7180 to the crystal to make sure I'm not over-driving it.