The concept of type and instance is a core Revit concept. Some elements need to vary while others need to remain coordinated. In conversations with customers I often hear that Revit could support the design process better. This usually means moving things around, testing ideas, and swapping out content in an unrestricted manner. Types add restriction yet if everything is an instance a lot of power is lost. Lets explore this topic and start by reviewing what Revit offers now.
Curtain Wall can define Grid and Mullion patterns quickly by type. Once a type is established you can choose to "un-pin" a sub-element to change its type, location or very existence.
These elements have a "Type Association" property which can be "Dependent" or "Independent". In this case one may end up with a mix or type driven elements and others that can vary from other type instances.
Grids and Mullions can also be added to a Curtain Wall which has a pattern in its type.
In both the above cases you end up with a Curtain Wall that is mixed as to whether its elements are defined by the type or instance.
What about Structure? "Beam System" has a command "Remove Beam System" which essentially makes all the beams behave as if they were placed manually.
Curtain Wall has a similar feature. If you swap a Curtain Wall Type with a pattern layout defined for one that is undefined you will be asked if you want to keep the sub-elements as instances or delete them.
This is a little different from removing a Beam System as the type still exists yet its just set to "None". The obvious question then is why doesn't Beam System have a layout rule option "None"? ...an unfortunate inconsistency. Beam system also places these properties at the instance level so it wasn't a type to begin with. It would probably be good for Beam System to match curtain wall and while we are at it for Curtain Wall to have a "Remove Type Layout" command.
The work-flow I see missing from this is there is no way to convert an instance into a type. Groups are the only thing I can think of. You select some items and Group them which wraps them in type goodness. The family editor also allows you to convert a parameter between type and instance. What if you could mess around with Grids and Mullions on a Curtain Wall, select some and define it as a type layout once you arrived at a nice pattern?
Is fluid conversion between type and instance a step on the path to better supporting design?
should there be a way to isolate and edit a type instance graphically?
...or both! Thoughts?