ISO C

[Rex Jaeschke]

> Recently, I was asked about the ISO C standard which I wasn't aware of.
> Can someone tell me when it was adopted (if it has)?  How does it
> differ from ANSI C?  Are there different levels like ISO Pascal?

As the US international rep to ISO C committee WG14 I can answer that.

ISO C is completed.

It is technically equivalent to ANSI C.

ANSI and ISO now use the same format for standards but did not when X3J11 
started so the ANSI std had to be significantly reformatted to make an ISO 
std document. Alas, the line number refs were not permitted to remain. This 
conversion has been done. I believe the document is wending its way through 
the ISO maze for final processing.

New work is continuing in WG14. Several national groups are heading up 
projects which will eventually result in one or more `normative addenda.' 

  The UK is adding clarification wording to many parts of the std but NOT
  adding/changing/deleting substantive stuff.

  The Japanese are working full steam on extra multibyte library support.

  The Danish are working on their alternate trigraph proposal.

It is expected that in a couple of years one or more of these addenda will
be completed and accepted by member nations in some form.  At that time
they will be added to the ISO C std and WILL HAVE the full weight of a
std.  At that point ISO C becomes a proper superset of ANSI C.  Whether
these addenda are retrofitted back into the ANSI std or not remains to be
seen.  (I foresee subsetting eventually for this reason: FIPS is based on
the current ANSI C std.  FIPS reflects the needs of govt agencies in the
US.  If a new ANSI std adopts all of the ISO addenda it's possible FIPS
could not use that new ANSI C std since alternate trigraphs or multibyte
support [for example] are NOT mandatory requirements for US govt business. 
So does FIPS then make its own std? No I think it better they require ANSi
C Level X and not the other options.) However, it does seem reasonable
that at some time in the future the ANSI std will take on the ISO format
to make it easier to reconcile the 2 stds.  At this stage David Prosser of
AT&T is the redactor of both stds.  I don't know how that will work once
the addenda come together since they are being produced by others.

At the Sep X3J11 meeting the officers of X3J11 proposed that X3J11 consider 
moving ALL NEW C STD WORK to the ISO arena AND ALSO, EVENTUALLY, 
INTERPRETATIONS. This is under consideration. The interpretations MUST be 
done by X3J11 for at least the foreseeable future but new work will almost 
certainly be restricted to the ISO level. Since it is acknowledged by both 
X3J11 and WG14 that the bulk of the technical expertise lies within X3J11 
the two committees have agreed to meet jointly once a year (every 2 
meetings under our current schedule). As such, a joint meeting will be held 
in Milan, Italy Dec 11-13.

Re my Numerical C Extentions Group. In Sep SPARC approved it as a working 
group within X3J11 (tentatively X3J11.1). There was 1 NO vote: that we 
should produce a std rather than a report.  The parent body X3 has yet to
do so.  In Nov, WG14 adopted NCEG as is as a rapporteur group within WG14. 
NCEG has the same role in both committees; to research numerical
extensions and publish a Technical report (tentatively sometime in 1992). 
So NCEG stuff has impact in the ISO arena now as well and it is mostly 
invention. However, its a report NOT a binding std.

Another issues being raised at ISO level is more open support for extended
national characters in identifiers and the idea of a compile-time locale.

Rex

----------------------------------------------------------------------------
Rex Jaeschke     |  Journal of C Language Translation  | C Users Journal
(703) 860-0091   |        2051 Swans Neck Way          | DEC PROFESSIONAL
rex at aussie.COM   |     Reston, Virginia 22091, USA     | Programmers Journal
----------------------------------------------------------------------------
Convener of the Numerical C Extensions Group (NCEG)
----------------------------------------------------------------------------