Each header reference page has a common layout of sections describing the interface. This layout is similar to the manual page or "man" page format shipped with most UNIX systems, and each header has sections describing the SYNOPSIS and DESCRIPTION. These are the two sections that relate to conformance.
Additional sections are informative, and add considerable information for the application developer. APPLICATION USAGE sections provide additional caveats, issues, and recommendations to the developer. RATIONALE sections give additional information on the decisions made in defining the interface.
FUTURE DIRECTIONS sections act as pointers to related work that may impact the interface in the future, and often cautions the developer to architect the code to account for a change in this area. Note that a future directions statement should not be taken as a commitment to adopt a feature or interface in the future.
The CHANGE HISTORY section describes when the interface was introduced, and how it has changed.
Option labels and margin markings in the page can be useful in guiding the application developer.