Typo in Calculator Tutorial Appendix A

Appendix A of the Calculator Tutorial says:

In order, to select cell which is a parent of a current cell, press Ctrl+Up. In order to select a child of a current cell, press Ctrl+Up.

I think that second one should be Ctrl+Down...

Feedback:

It occurred to me that the Calculator Tutorial would benefit from an introductory section (or link to such a section) that briefly describes development using MPS - i.e. how the idea for a DSL is realised using MPS, a generic overview and explanation of the sort of things that will be done in the tutorial.

For example:

The elements that make up an MPS project, how they interact and how they relate to the DSL.

Concepts - what they are, how they are used, how they contribute.

The various Editors - what part they play.

The Model - how it depends on the other elements.

Generators - how they fit in.

If I'd had a basic picture before starting the tutorial of what the pieces of the puzzle were, what they did, why they were needed, and how they fit together, I think I'd have had less trouble understanding it. The MPS editor is sufficiently different from the usual IDE editors that it takes a fair amount of mental effort just to mechanically follow the steps of the tutorial, without having to try and figure out how it all hangs together at the same time.