• What is archer?
• Where are the docs about "this" api?
• What, in specific, are you finding "confusing"?
• Where's the example of what you have tried (and how did it fail)?

Your last five OPs have show the same utter lack of detail, effort and code -- they're essentially all "gimme"s (Oops. my mistake: in 1 case, the post is an inappropriate root node clarifying a "gimme).

posting xml data
correcting output
Only printing multiline entries once
Removing Duplicates from a multiline entry
General Question on parsing a variable

And, NOT just BTW, most of those are FAQS, examples in Tutorials, or readily answered once the basics in perldoc perlintro are studied and understood.