A record that has only the Endeca.Action property set to DELETE (i.e., has no other properties) functions as a logical “Delete All” record. When the Record Store encounters such a record, the Record Store removes all records from a Record Store instance. This is useful when running a full crawl and you want to remove a generation of records before writing a new generation.

For example:

<RECORDS>
  <RECORD>
    <PROP NAME="Endeca.Action">
      <PVAL>DELETE</PVAL>
    </PROP>
  </RECORD>
  ...
</RECORDS>