Error Stack (available on error, empty and no depth otherwise)
  ERROR_DEPTH Function Returns the number of errors on the error stack
  ERROR_MSG Function Returns the error message of the error at the specified error depth
  ERROR_NUMBER Function Returns the error number of the error at the specified error depth

Backtrace (available on error, empty and no depth otherwise)
  BACKTRACE_DEPTH Function Returns the number of backtrace items in the backtrace
  BACKTRACE_LINE Function Returns the line number of the unit at the specified backtrace depth
  BACKTRACE_UNIT Function Returns the name of the unit at the specified backtrace depth

Call Stack
  DYNAMIC_DEPTH Function Returns the number of subprograms on the call stack
  LEXICAL_DEPTH Function Returns the lexical nesting level of the subprogram at the specified dynamic depth
  SUBPROGRAM Function Returns the unit-qualified name of the subprogram at the specified dynamic depth
  CONCATENATE_SUBPROGRAM Function Returns a concatenated form of a unit-qualified name
  OWNER Function Returns the owner name of the unit of the subprogram at the specified dynamic depth
  UNIT_LINE Function Returns the line number of the unit of the subprogram at the specified dynamic depth

Miscellaneous
  CURRENT_EDITION Function Returns the current edition name of the unit of the subprogram at the specified dynamic depth