# 6. How Things Work

This section explains how some of the functions inside PMIx perform their job. If you have questions about, for example, how device distances are computed, then you will find information on that subject here.

- 6.1. Session Directories
  - 6.1.1. Client Session Directories
  - 6.1.2. Tool and Server Session Directories
- 6.2. Distance Computation
- 6.3. Scheduler Integration
  - 6.3.1. Overview
- 6.4. Process Sets and Groups
  - 6.4.1. Overview
  - 6.4.2. Process Sets
  - 6.4.3. Group Construction
- 6.5. Resolving Peers and Nodes
- 6.6. How to Add a PMIx Datatype
  - 6.6.1. Step 1: Definitions
  - 6.6.2. Step 2: Buffer Operations
  - 6.6.3. Step 3: Random Things