Question about TOMAHAWK datatable example

[ying lcs]

i find a TOMAHAWK datatable example like following. What I don't understand is :
why the column name on browser is 'Username', 'Full Name', 'E-mail', 'Enabled'

these names are different from the 'columnname' in the tomahawk, right?

Thank for any pointers.

<t:dataTable id="users" var="user" style="margin-top: 10px"
   value="#{userList.users}" rows="25" sortColumn="#{userList.sortColumn}"
   sortAscending="#{userList.ascending}" styleClass="scrollerTable table"
   headerClass="standardTable_Header"
rowClasses="standardTable_Row1,standardTable_Row2"
   
columnClasses="standardTable_Column,standardTable_Column,standardTable_Column,standardTable_Column,standardTable_ColumnCentered">
   <t:column width="25%">
       <f:facet name="header">
           <t:commandSortHeader columnName="username" arrow="true">
               <h:outputText value="#{text['user.username']}" />
           </t:commandSortHeader>
       </f:facet>
       <h:commandLink action="#{userForm.edit}" value="#{user.username}">
           <f:param name="username" value="#{user.username}"/>
           <f:param name="from" value="list"/>
       </h:commandLink>
   </t:column>
   <t:column width="34%">
       <f:facet name="header">
           <t:commandSortHeader columnName="fullName" arrow="true">
               <h:outputText value="#{text['activeUsers.fullName']}" />
           </t:commandSortHeader>
       </f:facet>
       <h:outputText value="#{user.fullName}" />
   </t:column>
   <t:column width="25%">
       <f:facet name="header">
           <t:commandSortHeader columnName="email" arrow="true">
               <h:outputText value="#{text['user.email']}" />
           </t:commandSortHeader>
       </f:facet>
       <h:outputLink value="mailto:#{user.email}";>
           <h:outputText value="#{user.email}" />
       </h:outputLink>
   </t:column>
   <t:column width="16%">
       <f:facet name="header">
           <t:commandSortHeader columnName="enabled" arrow="true">
               <h:outputText value="#{text['user.enabled']}" />
           </t:commandSortHeader>
       </f:facet>
       <h:selectBooleanCheckbox value="#{user.enabled}" disabled="true"/>
   </t:column>
</t:dataTable>