AC warning messages

When ibischk3 issues a warning like:

WARNING - Model 'LVT162245_IO': TYP AC Rising Endpoints ( 0.01V, 2.45V) not within
          0.049V (2%) of ( 0.01V, 2.37V) on VI curves for 50 Ohms to 0V

where do the expected limits (0.01V, 2.37V) come from? The reason I ask is
that I am getting a warning more like:

WARNING - Model 'ECLout': TYP AC Rising Endpoints (-1.72V, -0.98V) not within
          0.015V (2%) of (-2.00V, -2.00V) on VI curves for 50 Ohms to -2V

where the upper and lower limits are the same, and that simply doesn't make sense.

Also: how serious a problem is this? Do some or all simulators have problems with
this sort of warning?

-- 
Kim Helliwell
Senior CAE Engineer
Acuson Corporation
Phone: 650 694 5030  FAX: 650 943 7260