Influences how the property values are escaped; see Handling Special XML Characters.
The "MIXED" value causes a change in the schema, as compared to the other possible values. Consider the following class:
Class Schema.CONTENT Extends (%RegisteredObject, %XML.Adaptor)
{
Parameter XMLTYPENAMESPACE = "mytypes";
Property Property1 As %String;
Property Property2 As %String(CONTENT = "STRING");
Property Property3 As %String(CONTENT = "ESCAPE");
Property Property4 As %String(CONTENT = "MIXED");
}
If we generate a schema for the namespace used here, we see the following:
<?xml version="1.0" encoding="UTF-8"?>
<schema xmlns="http://www.w3.org/2001/XMLSchema" xmlns:s="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified" targetNamespace="mytypes">
<complexType name="CONTENT">
<sequence>
<element minOccurs="0" name="Property1" type="s:string"/>
<element minOccurs="0" name="Property2" type="s:string"/>
<element minOccurs="0" name="Property3" type="s:string"/>
<element name="Property4">
<complexType mixed="true">
<choice maxOccurs="unbounded" minOccurs="0">
<any processContents="lax"/>
</choice>
</complexType>
</element>
</sequence>
</complexType>
</schema>
Notice that the three of these properties have the same type information, because XML treats them in the same way. InterSystems IRIS, however, treats the properties differently as described in Handling Special XML Characters.
If you use the object as input or output for a web method, and SoapBodyUse is encoded for that method, then InterSystems IRIS treats mixed content like string content, the default. That is, if you specify CONTENT as "MIXED", that value is ignored.