PT-Scotch and libPTScotch 6.0 User’s Guide. This document describes the capabilities and operations of PT-Scotch and libScotch, a software package and a software library which compute parallel static mappings and parallel sparse matrix block orderings of distributed graphs. It gives brief descriptions of the algorithms, details the input/output formats, instructions for use, installation procedures, and provides a number of examples. PT-Scotch is distributed as free/libre software, and has been designed such that new partitioning or ordering methods can be added in a straightforward manner. It can therefore be used as a testbed for the easy and quick coding and testing of such new methods, and may also be redistributed, as a library, along with third-party software that makes use of it, either in its original or in updated forms.