XMI24 — 4.8.4

4.8.4 has:
"For properties with default values, the default value should be the XML string representation to be placed in the schema.
Default values for properties should be specified in schemas with care since XML allows the processor reading the
document the option of not processing a schema as an optional optimization. When tools skip processing the schema, they
do not obtain the default value of XML attributes. Instead, they would have to know the default value from understanding
the model."
This largely dates from MOF 1.x which did not have default values (but XMI allowed them to be specified in the XSD). Therefore the 'with care' proviso no longer applies and so the text should be:
"For Properties with default values, the XML string representation is placed in the schema."
In fact this makes the tag org.omg.defaultValue redundant (and potewntially in conflict with the metanmodel) - the tag should be removed from the spec (e.g. in table 4.1).

Follow proposal and remove the “with caution provision” and remove tag org.omg.xmi.defaultValue.
Furthermore the org.omg.org.fixedValue tag is pointless – it was only ever used for xmi:version which has been deleted by another resolution.