anchor.diff:  [options="header", cols="1,3,1"]
   |=================
   | Element | Description | Required
  +|doctype|The document type of the emitted documents. For details of this element, see <<actors.all.children.doctype, "Doctype element's attributes">> in "All filter" section. |No; at most one can be specified
   |transform|A _Transform_ sink. .4+| No; at least one sink required
   |all|An _All_ sink.
   |snip|A _Snip_ sink.
  
positive.code: [options="header", cols="1,3,1"]
  |=================
  | Element | Description | Required
  |transform|A _Transform_ sink. .4+| No; at least one sink required
  |all|An _All_ sink.
  |snip|A _Snip_ sink.
  |output|An _Output_ sink.
  |=================
  
  
  [[actors.snip]]
  === Snip filter
  
negative.code:     <all root="flora">
        <transform style="flora/styles/to-genera.xsl">
          <snip select="/genera/genus">
            <doctype systemid="genus.dtd"/>
            <output destdir="flora/genera" refer="/genus/@name">
              <globmapper from="*" to="*.xml"/>
            </output>
  