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SD3 - Data Types [fmt]

From: Jon Bosak <bosak@atlantic-83.Eng.Sun.COM>
Date: Fri, 16 May 1997 13:51:27 -0700
Message-Id: <199705162051.NAA15724@boethius.eng.sun.com>
To: w3c-sgml-wg@w3.org
 From: Jean Paoli <jeanpa@microsoft.com>
 To: "'w3c-sgml-wg@w3.org'" <w3c-sgml-wg@w3.org>
 Subject: SD3 - Data Types
 Date: Thu, 15 May 1997 21:14:17 -0700


 SD3 - Data Types
 -------------------------------

 For many data processing applications, knowing the semantics of an
 element is not enough. Certain typical types of data, such as numbers
 and dates, form the basic measurements of whatever it is their
 elements represent. These types imply a typical sort order, an
 opportunity for efficient storage, and a grammar beyond XML.

 Proposal: (With special thanks to Tim Bray's paper
 "http://www.textuality.com/xml/typing.html"). Define a standard
 attribute, XML-TYPE, based on SQL data types. Valid values are CHAR,
 VARCHAR, INTEGER, FLOAT, DECIMAL, DATE, TIME and TIMESTAMP. Numbers
 and dates, times, etc.  will have implied text representations given
 by some t.b.d. ISO standards (e.g. ISO 8601::1988). At a minimum,
 float formats must allow both scientific and non-scientific formats
 (e.g. "12.34" and "0.1234E+2".) If no XML-TYPE attribute is given,
 VARCHAR is default.

 These data types have the effect of subclassing the contents of any
 element whose content type is ANY or MIXED. (More generally, I think
 of xml-type as inline subclassing of the contents of any element; the
 subclassing must be compatible with the element's content spec.)

 Many of these types can be qualified by further attributes. Here is a
 first-cut:

 <!ELEMENT VARCHAR (#PCDATA)>
	 <!ATTLIST CHAR XML-MAXSIZE CDATA> 

 <!ELEMENT CHAR (#PCDATA)>
	 <!ATTLIST CHAR 
				 XML-MAXSIZE CDATA 
				 XML-SIZE CDATA #IMPLIED >

 <!ELEMENT DECIMAL (#PCDATA)>
	 <!ATTLIST DECIMAL 
				 XML-DIGITS-R CDATA 4 
				 XML-DIGITS-TOTAL CDATA 18 
				 XML-SCALE CDATA 0 >

 <!ELEMENT INTEGER (#PCDATA)>
	 <!ATTLIST INTEGER
				 XML-DIGITS-R CDATA #FIXED 0 
				 XML-DIGITS-TOTAL CDATA 9 >

 <!ELEMENT FLOAT (#PCDATA)>
	 <!ATTLIST FLOAT XML-BITS CDATA 64 >

 <!ELEMENT TIME (#PCDATA)>

 <!ELEMENT DATETIME (#PCDATA)>
	 <!ATTLIST DATETIME XML-ZONE ( false | true ) true >

 <!ELEMENT DATE (#PCDATA)>
	 <!ATTLIST DATE XML-ZONE ( false | true ) true >

 Here is an example of data types in action:

 <LINEITEM XML-ID="L1">
	 <NAME>I, the Jury</NAME>
	 <AUTHOR>Spillane, Mickey</AUTHOR>
	 <PRICE xml-type="DECIMAL">2.95</PRICE>
	 <PUBLICATION-DATE xml-type="DATE">19470101</PUBLICATION-DATE>
	 <MANF-CODE><*xml-type xml-size=12>CHAR</>451-AE1396 </MANF-CODE>
	 </LINEITEM >


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Received on Friday, 16 May 1997 16:51:58 UTC

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