Corrigendum #9

Doug Ewell doug at
Mon Jun 2 11:36:50 CDT 2014

Shawn Steele <Shawn dot Steele at microsoft dot com> wrote:

> So I’d prefer to see text that better permitted interchange with other
> components of an application’s internal system or partner system, yet
> discouraged use for interchange with "foreign" apps.

If any wording is to be revised, while we're at it, I'd also like to see
a reaffirmation of the proper relationship between private-use
characters and noncharacters. I still hear arguments that private-use
characters are to be avoided in public interchange at all costs, as if
lack of knowledge of the private agreement, or conflicting
interpretations, will cause some kind of major security breach. At the
same time, the Corrigendum seems to imply that noncharacters in public
interchange are no big deal. That seems upside-down.

Mark Davis �� <mark at macchiato dot com> replied:

> The problem is where to draw the line. In today's world, what's an
> app? You may have a cooperating system of "apps", where it is
> perfectly reasonable to interchange sentinel values (for example).

Correct. Most people wouldn't consider a cooperating system like that
quite the same as true public interchange, like throwing this ���
into a message on a public mailing list.

Since the Corrigendum deals with recommendations rather than hard
requirements, SHOULDs rather than MUSTs, it doesn't seem that a bright
line is really needed.

> I agree with Markus; I think the FAQ is pretty clear. (And if not,
> that's where we should make it clearer.)

But the formal wording of the standard should reflect that clarity,

Doug Ewell | Thornton, CO, USA | @DougEwell

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