Querying existence

hasLeaf( xmp-path : String, prefix-map : Map ) : Boolean: Returns true if there is a leaf property at the XMP location path.
hasStruct( xmp-path : String, prefix-map : Map ) : Boolean: Returns true if there is a structure property at the XMP location path.
hasArray( xmp-path : String, prefix-map : Map ) : Boolean: Returns true if there is an array property at the XMP location path.
hasAltTextArray( xmp-path : String, prefix-map : Map ) : Boolean: Returns true if there is an Alt-Text array property at the XMP location path (that is, an array property of type "Alt" with leaf properties as children).
getArrayItemCount( xmp-path : String, prefix-map : Map ) : Number: Returns the number of items in the array at the XMP location path or 0 if there is no such property or if it is not an array.