Primitive types oddity?

[Robert Goldman]

Looking for all the user-defined types in a program, I issue the query

?X :: \object.

The results are as I expect, with one exception: \long is listed as a subtype of \object.

According to the Ergo manual: 

"This type name has synonyms: ’http://www.w3.org/2001/XMLSchema#long’ and \int." (p. 269)

So surely I should either get both \int and \long or neither, yes?

I don't actually see any definition of \object in the manual. The only mentions that my pdf search finds are on p. 20 and on a number of pages that provide information about the type signatures of other primitive types.

I suspect that this is because it just seemed obvious what \object was, but it would be helpful to be more explicit.  Apologies if there's something in the manual that I missed.