RegExp Help: [:cntrl:] not working

I'm trying to preg_split() text between "<page>". I used the following but can't get the regular expression to work: $content = "blah blah <page> blah blah blah"; $paged = preg_split( "[[:cntrl:]*]<page>[[:cntrl:]*]", $content ); I also tried the following... $content = "blah blah <page> blah blah blah"; $paged = preg_split( "[:cntrl:]<page>[:cntrl:]", $content ); ...and... $content = "blah blah <page> blah blah blah"; $paged = preg_split( "[[:cntrl:]]<page>[[:cntrl:]]", $content ); But none of these work. Can someone tell me what's wrong? I just want to split the text on "<page>" and include any line feeds that may have been put in before or after the "<page>" text. Thanks.