question: private static int lookupQualSelector ( XMPNode arrayNode , String qualName , String qualValue , int aliasForm ) throws XMPException { if ( XML_LANG . equals ( qualName ) ) { qualValue = Utils . normalizeLangValue ( qualValue ) ; int index = XMPNodeUtils . lookupLanguageItem ( arrayNode , qualValue ) ; if ( index < 0 && ( aliasForm & AliasOptions . PROP_ARRAY_ALT_TEXT ) > 0 ) { XMPNode langNode = new XMPNode ( ARRAY_ITEM_NAME , null ) ; XMPNode xdefault = new XMPNode ( XML_LANG , X_DEFAULT , null ) ; langNode . addQualifier ( xdefault ) ; arrayNode . addChild ( 1 , langNode ) ; return 1 ; } else { return index ; } } else { for ( int index = 1 ; index < arrayNode . getChildrenLength ( ) ; index ++ ) { XMPNode currItem = arrayNode . getChild ( index ) ; for ( Iterator it = currItem . iterateQualifier ( ) ; it . hasNext ( ) ; ) { XMPNode qualifier = ( XMPNode ) it . next ( ) ; if ( qualName . equals ( qualifier . getName ( ) ) && qualValue . equals ( qualifier . getValue ( ) ) ) { return index ; } } } return - 1 ; } }
target:  Searches for a qualifier selector in a node: [?qualName="value"] - an element in an array, chosen by a qualifier value. No implicit nodes are created for qualifier selectors,  except for an alias to an x-default item.