We could imagine a base class for this information that contains:

• Species/Group Identification

• Location

• Area type/habitat type

• Counts or estimates of population

• Observations

From that we could construct the following complex type:

<xs:complexType name="BioDataEntry">
<xs:sequence>
<xs:element ref="b:species"/>
<xs:element ref="b:location"/>
<xs:element ref="b:areatype"/>
<xs:element ref="b:counts" minOccurs="0"/>
<xs:element ref="b:observations" minOccurs="0"/>
</xs:sequence>
</xs:complexType>

How do we define the elements referred to above?