<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE s1 SYSTEM 'dtd/document.dtd'>
<s1 title="XML Schema">
	<s2 title="Introduction">
		<p>This package contains an implementation of the W3C XML 
		Schema Language, a recommendation of the Worldwide Web Consortium
        available in three parts:  
		<jump href="http://www.w3.org/TR/XMLSchema-0">XML Schema:  Primer</jump>  and
		<jump href="http://www.w3.org/TR/XMLSchema-1">XML Schema:  Structures</jump>  and
		<jump href="http://www.w3.org/TR/XMLSchema-2">XML Schema:  Datatypes</jump>. 
        We consider this implementation to be complete except for the
        limitations cited below.  The implementation has been
        extensively tested and known problem areas are set out below.
        In this document we also discuss our interpretation of the
        specifications where it seems to us particularly likely that
        others might arrive at a different interpretation.
        Please read this document before using this package.
        </p>
	</s2>

<s2 title="XML Schema Programmer's Guide">
<p>This section provides the following topics:</p>

<ul>
<li><jump href='#schema-limitations'>Limitations and known bugs</jump></li>
<li><link idref='faq-xs'>How do I?</link> -- 
	the most frequently asked questions
	about XML Schema that include some sample code.</li>
</ul>
</s2>
<anchor name='schema-limitations'/>
	<s2 title="Limitations">
        <ul>
            <li> Length, minLength, and maxLength facets are limited to the value 
            2147483647. Items larger than this limit will not be validated 
            correctly.</li>
            <li> Year and seconds values in date/time datatypes are limited to the 
            value 2147483647. Items larger than this limit will not be validated 
            correctly. </li>
        </ul>
    </s2>
    <s2 title='Problem Areas/Known Bugs'>
        <ul>
            <li> Due to changes in the specification for Decimals in
            JDK1.3, not all decimals that should be invalid according
            to the Schema specs may be found by the parser;</li>
            <li> For larger values of maxOccurs, a StackOverflowError may occur.
      	    The workaround for this problem, if your application permits it, 
      	    is to change the maxOccurs value to unbounded.</li>

        </ul>
    </s2>
    <s2 title='Interpretation of Areas that are Unclear or
            Implementation-Dependent'>
        <ul>
            <li> QName: the specification does not define the unit of length. We 
            chose to implement the length facet as being in units of XML characters 
            in the value space ( # of chars in namespace URI + ":" +
            local part );</li>
            <li> We have interpreted the specs as requiring
            &lt;keyref&gt; Identity Constraints to refer to
            &lt;key&gt; or &lt;unique&gt; identity constraints within
            the scope of the elements to which the &lt;keyref&gt; is
            attached.  This interpretation is at variance with the
            Schema Primer, which contains an example with a
            &lt;keyref&gt; declared on an element used inside the
            element of its corresponding &lt;key&gt;;</li>
        </ul>
    </s2>
	<s2 title="Other Notes">
        <p> The parsers contained in this package are able to read and
        validate XML documents with the grammar specified in either
        DTD or XML Schema format.  
		The schema is specified by the xsi:schemaLocation or
		xsi:noNamespaceSchemaLocation attribute on the root 
		element of the document. The xsi prefix must be bound to the 
		Schema document instance namespace, as specified by the
		Recommendation. See the sample provided in the
		Usage section.</p>
        <p> As of version 2.2.1, it is hoped that Xerces-J will always 
        be able to parse the Schema for Schemas current at the time of the product's release.  As of version
        2.2.1, this implies inserting special logic to permit the presence of
        the built-in Schema datatypes in this particular schema; an
        issue has been raised with the Schema Working Group, in hopes the document
        will be modified so that the built-in types are no
        longer presented as global components.  Thus, anyone planning
        to rely on the Schema for Schemas should be aware that the
        possibility exists that a change of this sort might be made in the future.  
        </p>
	</s2>
</s1>
