[JBB]

I can only agree that cloning/aliasing is a much-needed feature.

Here's an example: you're in the legal profession, and are outlining some deposition questions for a common case amongst several witnesses. Some of the questions will be asked of each witness. Others will be unique to the various witnesses. A perfect use of aliasing/cloning.

I understand the difficulty in getting it to work with custom column types. My suggestion would be to handle that later. Get it working without it first.