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RE: Query on Unicode and IGES.

My original query was on Unicode support for IGES characters. IGES, a
USA Computer-Aided-Design (CAD) exchange standard, defines a number
of odd characters that I need to support. As part of an
internationalization effort, I'd like to use Unicode for all internal
text strings, but it appeared that a number of geometric tolerance
characters defined in IGES were not in Unicode, hence my query.

A number of characters that seem to match between Unicode and IGES include
the following:

Unicode                          IGES

U+2197 Upper Right Arrow         Circular Runout     FC 68 (1001, 1003)
U+2205 Empty Set                 Diameter            FC 6E (1001, 1003)
U+2248 Almost Equal To           Approx. Equal       FC 6E (1002)
U+22A5 Up Tack                   Perpendicularity    FC 6C (1001)
U+2295 Circled Plus              Position            FC 6A (1001, 1003)
     (In the IGES character, the plus extends beyond the circle. In
      U+2295, the plus does not. CAD folks are usually very picky about
      these things.)

(IGES seems to map all these characters into the ASCII range
using a set of code pages: 1, 1001, 1002 and 1003. My knowledge of
IGES isn't that great, though.)

In addition, there's some odd IGES characters that I could find no
match (close or otherwise) in Unicode, including:

* Total Runout FC 74 (1003), which looks like a horizontal bar at the
bottom of the character, with a arrow going in the North East direction
coming from each end of the horizontal bar.

* Cylindricity FC 67 (1001, 1003), which looks like a small circle
(centered in the character cell) with two parallel diagonal lines
going from the bottom of the character cell and touching the bounds
of the circle. These lines go in a North East direction.

(Both of these characters are in Unicode 1.1, see below.)


Responses

What follows is a summary of the answers I received. (I summarized for
two reasons: first, to cut down on the space and second, because a few
of the replies were sent via private email and I'm uncomfortable posting
such messages to a public forum.) Any errors are entirely my own. Thanks
again to all who responded.


* Mark Grand (mdg@crl.com) mentioned that I could place any missing glyphs
into the Unicode Private Use Area, which is intended for such needs.

* Chuck Houpt (chuck@lec.com) also mentioned the same point, and added that
just using the Private Use Area isn't enough if I want to exchange such
Unicode-encoded data with other CAD/CAM software (this is the main reason
I was looking for signs of IGES characters supported by the Unicode
character set-Eric). He suggested organizing an interest group among
such vendors to first agree on a mapping to the Private Use Area and
then, in the long run, propose the missing IGES characters to the
Unicode Consortium.

* Doug Merritt (doug@netcom.com) adds that the actual visual look of the
characters in Unicode depend on the font used to render the characters,
not necessarily on the character set. Because of this, I'll need an
"IGES" font to display the characters. (Just as Chinese and Japanese
fonts may have different-looking glyphs for the same Unicode characters
from the Han unification area. In a similar example, Times Roman and
Helvetica display the same characters, but use different glyphs.)

Doug then stressed that the precise appearance in the Unicode Standard
(vols. 1-2, Addison-Wesley, 1991, 1992) isn't the issue. The real issue
is finding characters with a reasonably close semantic meaning to the
IGES characters.

* Joseph D. Becker (Joseph_D._Becker.OSBU_North@xerox.com) explained that
Unicode 1.1 (a later version than the 1.0 books) has many of the IGES
characters already in it, including:

U+2300	DIAMETER SIGN
U+232D	CYLINDRICITY
U+2330	TOTAL RUNOUT

(And there was much rejoicing.)

The DIAMETER SIGN, U+2300, replaces an earlier Unicode 1.0 character.
With Unicode 1.1, Unicode and ISO 10646-1 have the same character content
and names.

And, Joe pointed out that I goofed in my original query:

	U+2316 POSITION INDICATOR was already in Unicode 1.0.

Joe added that you can get the Unicode 1.1 name list via anonymous FTP
from unicode.org in the /pub/MappingTables/Unicode_1.1_Tables directory.

Thanks again. If I missed anyone, I apologize--I've been in too many
meetings today and my mind is frazzled.

-Eric

--
Eric F. Johnson           email: johnsone@camax.com   ERROR_TOO_MANY_SECRETS
CAMAX Systems, Inc.       phone: +1 612 854 5300      -The maximum number of
7851 Metro Parkway        fax:   +1 612 854 6644      secrets has been
Minneapolis, MN 55425 USA                             exceeded.-Win32 (NT) API.