XSD mapping pattern
Codelists are given by the stereotype <<codelist>>. As it can be seen from the diagram below, for each <<codelist>> type, there also is a <<datatype>> class, which defines the nilReason attribute.
Example
First, the <<codelist>> class is converted into a simpleType in the XSD:
<simpleType name="CodeAircraftEngineBaseType">
<annotation>
<appinfo><gml:description>A
code indicating the type of aircraft engine (for example, jet, piston,
turbo).</gml:description></appinfo>
</annotation>
<union>
<simpleType>
<restriction base="xsd:string">
<enumeration value="JET">
<annotation>
<appinfo><gml:description>Jet Engine</gml:description></appinfo>
</annotation>
</enumeration>
<enumeration value="PISTON">
<annotation>
<appinfo><gml:description>Piston Engine</gml:description></appinfo>
</annotation>
</enumeration>
<enumeration value="TURBOPROP">
<annotation>
<appinfo><gml:description>Turbo Propeller Engine</gml:description></appinfo>
</annotation>
</enumeration>
<enumeration value="ALL">
<annotation>
<appinfo><gml:description>All aircraft engine types.</gml:description></appinfo>
</annotation>
</enumeration>
</restriction>
</simpleType>
<simpleType>
<restriction base="string">
<pattern value="OTHER(\w|_){1,58})?"/>
</restriction>
</simpleType>
</union>
</simpleType>
Note that the simple data types is declared as a union between the enumerated values declared in the UML model (with the exception of the value "OTHER") and a string with the pattern "OTHER(:(\w|_){1,58})?". This enables <<codelist>> data types to include values that are not supported by the enumeration list. For example, an electric engine type could be encoded as "OTHER:ELECTRIC".
In addition, a complex type is defined, including the declaration of the nilReason attribute:
<complexType name="CodeAircraftEngineType">
<simpleContent>
<extension base="aixm:CodeAircraftEngineBaseType">
<attribute name="nilReason" type="gml:NilReasonEnumeration"/>
</extension>
</simpleContent>
</complexType>
