Sorry for the late reply.

Anyway: map works by calling a codeblock for each element of the supplied list and passes the element as $_. (click the link to see the official docs for map)

name() is mentioned on the XML::Twig documentation, in the (very long and not very well structured) section called METHODS. It just returns the "tag-name" for an XML::Elt, i.e. for <tagname attr="value" att2="value2"/> it returns the string "tagname".

The code I supplied basically creates an anonymous subroutine, or code block, for each tag-name you're interested in and XML::Twig will call that subroutine whenever it finds a tag with that tag-name, passing an object (update: as $_ - which is generally considered poor style, but makes for short and possibly more readable code) that represents that tag (and you can call ->name() on that object to retrieve the tag name)