XMI24 — Fixed-point issues with the definition of default values for literals

The definition of LiteralBoolean in the XMI for UML1.5 includes the following:

<packagedElement xmi:type="uml:Class" xmi:id="LiteralBoolean" name="LiteralBoolean">

<ownedAttribute xmi:type="uml:Property" xmi:id="LiteralBoolean-value" name="value" visibility="public">

<defaultValue xmi:type="uml:LiteralBoolean" xmi:id="LiteralBoolean-value-_defaultValue"/>

</ownedAttribute>

So the default value for value, which is correctly specified as false in the model, is specified by the absence of a value attribute as “the default value for LiteralBoolean::value” in the XMI. This is circular and ill-defined.

One issue is with the XMI specification. The rule that property values should not be serialized when they have their default value should not apply when those properties are being used to define default values for themselves.

This needs to be addressed.