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<div class="section" id="limitations">
<h1>Limitations<a class="headerlink" href="#limitations" title="Permalink to this headline">¶</a></h1>
<div class="section" id="things-that-work">
<h2>Things That Work<a class="headerlink" href="#things-that-work" title="Permalink to this headline">¶</a></h2>
<ul class="simple">
<li>Class constants corresponding to string enumeration constraints</li>
<li>Simple and complex type definitions</li>
<li>List and union datatypes</li>
<li>Constraints on (simple) datatypes (e.g., minInclusive, length)</li>
<li>Model groups and attribute groups</li>
<li>Complex content models (all, sequence, choice); minOccurs and maxOccurs</li>
<li>Abstract types, <a class="reference external" href="http://www.w3.org/TR/xmlschema-1/#xsi_type">xsi:type</a>,
substitution groups</li>
<li>Nillable elements with <a class="reference external" href="http://www.w3.org/TR/xmlschema-1/#xsi_nil">xsi:nil</a></li>
<li>Namespace qualified attributes and elements</li>
<li>Documentation annotations present in the schema are converted to Python
docstrings in the generated bindings.</li>
<li>Pattern constraints (as long as the simple type derives from something
that is represented as a Python string)</li>
</ul>
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<div class="section" id="things-that-don-t-work">
<h2>Things That Don’t Work<a class="headerlink" href="#things-that-don-t-work" title="Permalink to this headline">¶</a></h2>
<div class="section" id="but-could-someday">
<h3>...but could someday<a class="headerlink" href="#but-could-someday" title="Permalink to this headline">¶</a></h3>
<ul class="simple">
<li>Identity constraints (“key”, “unique”, “keyref”) are stored in the content
model, but are not used.</li>
<li><a class="reference external" href="http://www.w3.org/TR/xmlschema-1/#Wildcards">Wildcard elements</a> are
supported in the sense that classes that enable them in the content model
provide access to unrecognized values through the
<a class="reference internal" href="pyxb.binding.html#pyxb.binding.basis.complexTypeDefinition.wildcardElements" title="pyxb.binding.basis.complexTypeDefinition.wildcardElements"><code class="xref py py-obj docutils literal"><span class="pre">pyxb.binding.basis.complexTypeDefinition.wildcardElements</span></code></a> method.
Where the type of the node is recognized, it is converted to a Python
binding instance; otherwise, the xml DOM instance is stored. Although
namespace constraints are applied when checking for wildcard matches, the
process contents attribute of the wildcard is ignored.</li>
<li><a class="reference external" href="http://www.w3.org/TR/xmlschema-1/#ag-attribute_wildcard">Wildcard attributes</a> are supported
in much the same sense as wildcard elements: no constraints are checked,
and all are aggregated into the
<a class="reference internal" href="pyxb.binding.html#pyxb.binding.basis.complexTypeDefinition.wildcardAttributeMap" title="pyxb.binding.basis.complexTypeDefinition.wildcardAttributeMap"><code class="xref py py-obj docutils literal"><span class="pre">pyxb.binding.basis.complexTypeDefinition.wildcardAttributeMap</span></code></a>.
Values are uninterpreted Unicode strings.</li>
</ul>
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<div class="section" id="and-probably-never-will">
<h3>...and probably never will<a class="headerlink" href="#and-probably-never-will" title="Permalink to this headline">¶</a></h3>
<ul class="simple">
<li>The <a class="reference external" href="http://www.w3.org/TR/xmlschema-1/#modify-schema">redefine directive</a>
is not supported.</li>
<li>The ability to use templates to customize binding generation was promised
in the vision document, but after three years of no plausible use case it
is no longer part of the plan.</li>
</ul>
</div>
</div>
<div class="section" id="things-that-mostly-work-but-they-re-ugly">
<h2>Things That Mostly Work, But They’re Ugly<a class="headerlink" href="#things-that-mostly-work-but-they-re-ugly" title="Permalink to this headline">¶</a></h2>
<ul class="simple">
<li>The <a class="reference external" href="http://www.w3.org/TR/xmlschema-2/#duration">duration</a> type is based
on the Python <code class="docutils literal"><span class="pre">datetime.timedelta</span></code> class, which works reasonably well
for small deltas but does not handle month and year deltas. The PyXB
version records that information, but the <code class="docutils literal"><span class="pre">timedelta</span></code> functionality
(adding/substracting from <code class="docutils literal"><span class="pre">datetime</span></code> instances) does not incorporate
that portion of the delta. Negative durations also may not work properly.</li>
</ul>
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<h3><a href="index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">Limitations</a><ul>
<li><a class="reference internal" href="#things-that-work">Things That Work</a></li>
<li><a class="reference internal" href="#things-that-don-t-work">Things That Don’t Work</a><ul>
<li><a class="reference internal" href="#but-could-someday">...but could someday</a></li>
<li><a class="reference internal" href="#and-probably-never-will">...and probably never will</a></li>
</ul>
</li>
<li><a class="reference internal" href="#things-that-mostly-work-but-they-re-ugly">Things That Mostly Work, But They’re Ugly</a></li>
</ul>
</li>
</ul>
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