- From: Arnold, Curt <Curt.Arnold@hyprotech.com>
- Date: Mon, 15 Nov 1999 13:46:37 -0700
- To: "'www-xml-schema-comments@w3.org'" <www-xml-schema-comments@w3.org>
Maybe some one can enlighten me, but I see no value and significant complications due to the use of the minAbsoluteValue facet. I believe the complications are substantially severe enough and the benefits so nebulous that the facet should be removed to prevent its use. The maxAbsoluteValue facet does not concern me as much, but I do think it should be eliminated since the same goal can be accomplished using the existing minInclusive and maxInclusive facets. Here is a scenario: The schema author naively writes a minAbsoluteValue facet of 1.40239846e-45 for a datetype since he wants to support applications that use IEEE single precision. An engineering program that writes XML is written using a floating point datatype that supports greater precision must now check every value written against the schema underflow constraint to prevent validation errors. An engineering program that is written in greater than single precision is now subject to greater truncation errors since the document creator had to purposefully lose precision. A single precision engineering application avoids an underflow when the double precision value typically generated by the conversion factor is truncated to single precision. The fact is that an truncation underflow in a lower precision application is not such an extraordinary bad event that it justifies the additional burden on applications that use higher precision. What is so bad with letting the lower precision application taking a value of 1-e100 and truncating it to zero if and when it encounters it. If the schema author wants to support single precision, he can use a min and max constraint to prevent the value from getting outside of the +/-1e38 range and should tolerate underflows that may be generated from higher precision applications.
Received on Monday, 15 November 1999 15:48:57 UTC