SQL & PL/SQL

i know how to wrap a standalone unit....say for example if i want to wrap a procedure sample.prc
then from the command prompt i issue the following cmd


wrap iname=sample.prc oname=sample.plb


i want to know how to perform wrap of all procedures or packages at a time..(batch wrap)..first of all is it possible?

wat r the db objects that can be wrapped?

wat r the steps to be followed for wrapping the objects and how to unwrap?