Why Is A Wall Not A FamilyInstance?

[Anonymous]

I'm trying to understand how objects inserted into a Revit drawing are seen from an API point of view. 

I have a simple drawing that has two structural columns inserted, and two walls (that happen to have formed a corner, but not important right now). 

If I get a list of the selected elements, the two columns come out as FamilyInstance objects - Category = Structural Columns, Family = RSA-Rectangular Steel Angle-Column, Type = 200x200x24 RSA. Fits the format perfectly. 

But the walls come out differently. They do appears to have a category of Walls, so far so good; but then they are not FamilyInstance - they have their own object type, Wall. 

Why? Why do they not fit the same rules as other inserted objects and have a family and type? The API Wiki says they are of a system family, which makes sense - so why aren't they an instance of a [system] family type? 

I just wonder why the inconsistency. 

[augusto.goncalves]

Walls (and other types) are System Families, which are all defined by their own object.

As a reference point, if you cannot insert from a RFA file, then is not a FamilySymbol and FamilyInstance

[Fabian.OswaldS52TK]

There is a trick for this:

1. Create a project family in the model, here you can select the Wall category.
2. Search the project browser for the project family you have just created.
3. Right-click followed by Save...
4. You now have a family with the Wall category.