elevation becomes altitude

After a long hiatus, I'm back to my VisAD project! I'm trying to get some old code working with the latest version of VisAD and I'm having this problem.

I am trying to create some data sets with the following MathType:

(Time, ((Longitude, Latitude) -> (Overlay, Elevation)))

where "overlay" is something like temperature or precipitation. The overlays for some set of such data sets always cover the same geographic region, and thus I use the same elevation file for each one. My source data sets are in the form of text files, which I convert to NetCDF files with a small app I wrote. When I open a data set created in this way in the VisAD spreadsheet, I find that my elevation data have become "altitude." Why is this? How do I prevent it? My code to create the elevation MathType looks like this:

RealType elevation = RealType.getRealType("Elevation", SI.meter);