Annex H. Safety and Security

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This Annex addresses requirements for systems that are safety critical or have security constraints. It provides facilities and specifies documentation requirements that relate to several needs:

  • Understanding program execution;
  • Reviewing object code;
  • Restricting language constructs whose usage might complicate the demonstration of program correctness

Execution understandability is supported by pragma Normalize_Scalars, and also by requirements for the implementation to document the effect of a program in the presence of a bounded error or where the language rules leave the effect unspecified.

The pragmas Reviewable and Restrictions relate to the other requirements addressed by this Annex.


1  The Valid attribute (see 13.9.2) is also useful in addressing these needs, to avoid problems that could otherwise arise from scalars that have values outside their declared range constraints.

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