how to programatically define

[Brad Barton]

Since HVars appears in the Help menus, but I don't seem to be able to access from the catalog, it seems like a semi-documented function. Looks like a really nice way to define functions programatically if you want to create an environment for dealing with specific classes of equations.

Is there any documentation outside of the Help menus that shows these types of commands and how they're used?