Which version of Metis in ParMetis?

The ParMetis distribution includes (and builds) a separate Metis library. What is the relationship of this library to the Metis distribution (e.g., which version)? I'm wondering if for serial use I can just use this library directly (in which case I need a pointer to the appropriate user documentation), or is it a 'special' version intended only for indirect use via ParMetis.

Thanks!