[wg11] EXPRESS and P28 String Data Type issue

[Phil Spiby]

It has come to Eurostep's attention (whilst testing some of our P28
production capabilities) that there is an issue with the domain of the
string data type and the mapping of this data to P28 files.

The definition of the string data type is:
The string data type has as its domain sequences of characters. The
characters that are permitted as part of a string value are those characters
allocated to cells 08 to 0D and the graphic characters lying in the ranges
20 to 7E and A0 to 10FFFE of ISO/IEC 10646-1.

This definition was adopted in TC1 when the EXPRESS language was harmonized
with SGML and XML such that data in a CDATA section of SGML/XML was not
corrupted when passed into an EXPRESS based data structure. It now seems
that the P28 approach of mapping the EXPRESS string data type to a
normalised string removes this capability, since all formatting characters
(cells 08-0D) handled by a CDATA section and the EXPRESS data type are now
lost.

Basically the P28 mapping of data from EXPRESS is removing data from the
exchange file (since it is converting any formatting characters into
spaces).

Phil

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