Returns the number of items in a set.
<counter> <item> <list> <picture> <port> <sound> <text> <video> <xid>
The following displays the value of itemcount in a text stimulus:
<text sometext>
/ items= ("item = <% text.sometext.itemcount %>")
</text>
The following displays the value of itemcount in an instruction page:
<page somepage>
item = <% item.negativeitems.itemcount %>
</page>