Re: Design of commands operating on rectangular regions

[Juri Linkov]

> In order to follow all of this, especially since you now
> seem to be talking about user-level changes, could someone
> please specify (describe) the non-contiguous region feature,
> including how users can create and modify such a region
> interactively?

First you can select the non-contiguous region with
'C-x SPC', then extend it with the usual point motion keys,
then run one of the commands supporting such regions, e.g.
'C-x C-l' to downcase, 'M-%' to replace occurrences, 'C-u M-|'
to replace the region with the command output.

> And could you specify clearly the relation between this
> non-contiguous region feature and rectangles?  Presumably
> the former is more general but also allows some handling
> of rectangles (?).

Rectangles are a subset of non-contiguous regions that can be
expanded with other shapes, e.g. circular regions.