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Re: motion for July: reduce recommended options for signaling NaN character sequences
This is item 22 for July. - Dan
Date: Fri, 07 Jul 2006 16:10:57 -0700
From: Jim Thomas <jwthomas@xxxxxxxxxx>
Subject: motion for July: reduce recommended options for signaling NaN
character
sequences
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Dan, I'd like to make the following motion at the July meeting.
-Jim
-----------------
Motion: reduce recommended options for signaling NaN character sequences
Rationale:
This proposal reduces the number of recommended options for signaling
NaN character sequences. It provides clear direction to languages and
implementations, so that those that follow the recommendation will
support a minimal level of data sharing, that might include signaling
NaNs, via external character sequences. The specified signaling NaN
character sequences are recommended, but not required, to allow for
innovation and to not exclude implementations that conform except for
this support of the marginal signaling NaN feature. The extremely
flexible specification in the current draft, which was intended to
encompass the range of possible designs, is difficult to understand and
may promote gratuitous diversity.
Text:
In 5.13.1, paragraph 6, change the last two sentences from:
Conversion of a signaling NaN in internal format to an external
character sequence shall produce a language-defined sequence beginning
with "snan" or "nan" or a sequence that is equivalent except for case
(e.g. "sNaN" or "NANSIG" or "NaN"), with an optional preceding sign. If
the conversion of a signaling NaN does not produce a language-defined
representation of a signaling NaN, then the invalid exception should be
signaled.
to:
Conversion of a signaling NaN in internal format to an external
character sequence should produce a language-defined one of "snan" or
"nan" or a sequence that is equivalent except for case, with an optional
preceding sign. If the conversion of a signaling NaN produces "nan" or a
sequence that is equivalent except for case, with an optional preceding
sign, then the invalid exception should be signaled.
In 5.13.1, paragraph 7, change the last three sentences from:
Conversion of external character sequences beginning with "snan" or
"nan", regardless of case, with an optional preceding sign, should
produce a NaN. What (if any) NaN sequences represent signaling NaNs is
language defined. If the conversion of a language-defined sequence
representing a signaling NaN does not produce a signaling NaN, then the
invalid exception should be signaled.
to:
Conversion of an external character sequence "snan", regardless of case,
with an optional preceding sign, to an internal format should either
produce a signaling NaN or else produce a quiet NaN and signal the
invalid exception.