BPMN21 — Ambiguous statement about DataObjects and DataObjectReference

In section 10.3.1 there are some confusing statements about DataObjects and DataObjectReference. One statement reads "Data Object Reference cannot specify item definitions, and Data Objects cannot specify states." (page 215) and on the next page there is another statement that reads "Data Object elements can optionally reference a DataState element, which is the state of the data contained in the Data Object (see an example of DataStates used for Data Objects in Figure 7.8)." Can then DataObjects reference a state? Or is the "state" in the first sentence a different kind of state?

Furthermore the schema (http://www.omg.org/spec/BPMN/2.0/20100501/Semantic.xsd) specifies that the DataOjectReference may have a reference to the item definition:
<xsd:element name="dataObjectReference" type="tDataObjectReference" substitutionGroup="flowElement" />
<xsd:complexType name="tDataObjectReference">
<xsd:complexContent>
<xsd:extension base="tFlowElement">
<xsd:sequence>
<xsd:element ref="dataState" minOccurs="0" maxOccurs="1" />
</xsd:sequence>
<xsd:attribute name="itemSubjectRef" type="xsd:QName" />
<xsd:attribute name="dataObjectRef" type="xsd:IDREF" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>

And that the DataObject may have a state:
<xsd:element name="dataObject" type="tDataObject" substitutionGroup="flowElement" />
<xsd:complexType name="tDataObject">
<xsd:complexContent>
<xsd:extension base="tFlowElement">
<xsd:sequence>
<xsd:element ref="dataState" minOccurs="0" maxOccurs="1" />
</xsd:sequence>
<xsd:attribute name="itemSubjectRef" type="xsd:QName" />
<xsd:attribute name="isCollection" type="xsd:boolean" default="false" />
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>