It would be much simpler if each such character were clearly labelled in
the code charts etc. DO NOT USE!, and with its glyph presented on a grey
background or in some other way to indicate its special status.
I don't think people should be told so directly to NOT use an official Unicode character unless the character is actually deprecated.
Over the years recommendations about particular characters in the standard have sometimes changed and no-one can see all possible uses for characters or all ways that applications might use some of them.
But greying the chart area for deprecated characters and singleton canonical decomposable characters seems to me a good idea.
As to compatibility characters, remember some of them, for example spaces with varying widths, make essential differences in formatting. The standard warns applications not to be hasty in unifyng compatibility characters for presentation.
If it is not deprecated a character should be usable.
But some more obivous graphic indication would be nice to more obviously indicate that perhaps a user should think carefully about using that particular encoded character.
Jim Allan
