Rationale (XRAT)
Understanding the "Why" Behind the Specification
XRAT's core purpose is to assist in the review and understanding of the main text. It contains historical information, notes on recommended programming practices, and the reasoning behind why features were included or discarded by the standards developers.
Structure of XRAT
XRAT is organized in parallel to the normative volumes of the Base Specification, with a separate appendix for each of the three normative volumes, plus two additional appendices:
Appendix A: Rationale for XBD
Contains the reasoning and historical context for the Base Definitions volume.
Appendix B: Rationale for XSH
Covers the rationale for the System Interfaces volume.
Appendix C: Rationale for XCU
Explains the reasoning behind the Shell and Utilities volume.
Appendix D: Portability Considerations
Includes a report on user requirements and provides guidance to writers of profiles on using configurable options, limits, and optional behavior.
Appendix E: Subprofiling Considerations
Satisfies the requirement that the document address subprofiling and contains an example set of subprofiling options.