The following example queries for cases where the Expires field is either null or contains a value greater than or equal to the current date.
<Query>
<Where>
<Or>
<IsNull>
<FieldRef Name="Expires" />
</IsNull>
<Geq>
<FieldRef Name="Expires" />
<Value Type="DateTime">
<Today />
</Value>
</Geq>
</Or>
</Where>
<OrderBy>
<FieldRef Name="Modified" Ascending="FALSE" />
</OrderBy>
</Query>
The next example from the Schema.xml file for contacts lists specifies fields to display in the toolbar.
<ViewFields>
<FieldRef Name="LinkTitleNoMenu"></FieldRef>
<FieldRef Name="FirstName"></FieldRef>
<FieldRef Name="WorkPhone"></FieldRef>
<FieldRef Name="Email"></FieldRef>
</ViewFields>