The ContextRecord data structure describes the machine state at the time of an exception. This data structure is hardware dependent and is not portable. Therefore, as a rule, software should not use the information contained in this data structure. However, hardware dependent code, such as math libraries, can make use of this information to optimize certain operations.

For a hardware-initiated exception, ContextRecord contains the complete machine state at the time of the exception. For a software-initiated exception, ContextRecord contains the machine state at the time the software raised the exception.

The ContextRecord data structure consists of fields for the following:

• General purpose registers
  
• Segment registers
  
• The flags register
  
• The floating point environment and stack.

Note: With asynchronous exceptions (signal and termination exceptions), the context in ContextRecord is read-only. The exception handler can modify it, but the changes with be ignored.

With synchronous exceptions, changes to ContextRecord will be used when the context is restored.