PHP SimpleXML xpath: contains and position

Here is my PHP code: ``` $xml = new SimpleXMLElement('data.xml', null, true); $q = $xml->xpath('post/misc[contains(tags,"animal")][position() <= 2]'); ``` And here is the XML file: ``` <?xml version="1.0" encoding="UTF-8" ?> <posts> <post> <id>1</id> <misc> <tags>animal,tiger</tags> <prio>0.5</prio> </misc> </post> <post> <id>2</id> <misc> <tags>plant,coconut</tags> <prio>0.5</prio> </misc> </post> <post> <id>3</id> <misc> <tags>animal,lion</tags> <prio>0.5</prio> </misc> </post> <post> <id>4</id> <misc> <tags>animal,monkey</tags> <prio>0.5</prio> </misc> </post> </posts> ``` How do I get the 2 first elements where it's tags contains 'animal' ? The xpath result should be `post:id=1` and `post:id=3`, but it's seen to return all elements which contains `animal`.