How to define spatial domains?

Discussion created by shaningesri on Nov 2, 2011
Latest reply on Nov 2, 2011 by MKennedy-esristaff
In old verion of ArcGIS Desktop, I could manually define Spatial Domains (or X/Y Domains) when I created a Dataset using ArcCatalog.  Now I am using V10.  When I created a dataset, I chosen WGS_1984_Web_Mercator_Auxiliary_Sphere.  Then the X/Y domain is automatically defined.  For example,
Min X = -20037700
Max X = 900699887774.099
Min Y = -30241100
Max Y = 900689684374.099
The unit is meter.  It looks that the values of Max X and Max Y do not make sense.  Max X =  900,699,887 km, which is 225 times longer than the earth equator's perimeter (about 40,000 km).
Can anyone explain this issue?  Besides, is there a way to manually define the X/Y domain values using V10?  Thanks.