Definitions =========== * **Source tree:** The tree where the PMIx source code is located. It is typically the result of expanding an PMIx distribution source code bundle, such as a tarball. * **Build tree:** The tree where PMIx was built. It is always related to a specific source tree, but may actually be a different tree (:ref:`since PMIx supports VPATH builds `). Specifically, this is the tree where you invoked ``configure``, ``make``, etc. to build and install PMIx. * **Installation tree:** The tree where PMIx was installed. It is typically the "prefix" argument given to PMIx's ``configure`` script; it is the directory from which you run installed PMIx executables.