Implementation-Defined Characteristics
Author: JTC1/SC22/WG9/ARG, by Randall Brukardt, ARG Editor

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# Annex M

## (informative)

# Implementation-Defined Characteristics

1
The Ada language allows for certain machine dependences in a controlled manner. Each Ada implementation must document all implementation-defined characteristics:
2

- Whether or not each recommendation given in Implementation Advice is followed. See 1.1.2(37).

3

- Capacity limitations of the implementation. See 1.1.3(3).

4

- Variations from the standard that are impractical to avoid given the implementation's execution environment. See 1.1.3(6).

5

- Which code_statements cause external interactions. See 1.1.3(10).

6

- The coded representation for the text of an Ada program. See 2.1(4).

7

- The control functions allowed in comments. See 2.1(14).

8

- The representation for an end of line. See 2.2(2).

9

- Maximum supported line length and lexical element length. See 2.2(14).

10

- Implementation-defined pragmas. See 2.8(14).

11

- Effect of pragma Optimize. See 2.8(27).

12

- The sequence of characters of the value returned by S'Image when some of the graphic characters of S'Wide_Image are not defined in Character. See 3.5(37).

13

- The predefined integer types declared in Standard. See 3.5.4(25).

14

- Any nonstandard integer types and the operators defined for them. See 3.5.4(26).

15

- Any nonstandard real types and the operators defined for them. See 3.5.6(8).

16

- What combinations of requested decimal precision and range are supported for floating point types. See 3.5.7(7).

17

- The predefined floating point types declared in Standard. See 3.5.7(16).

18

- The small of an ordinary fixed point type. See 3.5.9(8).

19

- What combinations of small, range, and digits are supported for fixed point types. See 3.5.9(10).

20

- The result of Tags.Expanded_Name for types declared within an unnamed block_statement. See 3.9(10).

21

- Implementation-defined attributes. See 4.1.4(12/1).

22

- Any implementation-defined time types. See 9.6(6).

23

- The time base associated with relative delays. See 9.6(20).

24

- The time base of the type Calendar.Time. See 9.6(23).

25

- The timezone used for package Calendar operations. See 9.6(24).

26

- Any limit on delay_until_statements of select_statements. See 9.6(29).

27

- Whether or not two nonoverlapping parts of a composite object are independently addressable, in the case where packing, record layout, or Component_Size is specified for the object. See 9.10(1).

28

- The representation for a compilation. See 10.1(2).

29

- Any restrictions on compilations that contain multiple compilation_units. See 10.1(4).

30

- The mechanisms for creating an environment and for adding and replacing compilation units. See 10.1.4(3).

31

- The implementation-defined means, if any, of specifying which compilation units are needed by a given compilation unit. See 10.2(2).

32

- The manner of explicitly assigning library units to a partition. See 10.2(2).

33

- The manner of designating the main subprogram of a partition. See 10.2(7).

34

- The order of elaboration of library_items. See 10.2(18).

35

- Parameter passing and function return for the main subprogram. See 10.2(21).

36

- The mechanisms for building and running partitions. See 10.2(24).

37

- The details of program execution, including program termination. See 10.2(25).

38

- The semantics of any nonactive partitions supported by the implementation. See 10.2(28).

39

- The information returned by Exception_Message. See 11.4.1(10).

40

- The result of Exceptions.Exception_Name for types declared within an unnamed block_statement. See 11.4.1(12).

41

- The information returned by Exception_Information. See 11.4.1(13).

42

- Implementation-defined check names. See 11.5(27).

43

- Any restrictions placed upon representation items. See 13.1(20).

44

- The interpretation of each aspect of representation. See 13.1(20).

45

- The meaning of Size for indefinite subtypes. See 13.3(48).

46

- The default external representation for a type tag. See 13.3(75/1).

47

- What determines whether a compilation unit is the same in two different partitions. See 13.3(76).

48

- Implementation-defined components. See 13.5.1(15).

49

- If Word_Size = Storage_Unit, the default bit ordering. See 13.5.3(5).

50

- The contents of the visible part of package System and its language-defined children. See 13.7(2).

51

- The contents of the visible part of package System.Machine_Code, and the meaning of code_statements. See 13.8(7).

52

- The effect of unchecked conversion. See 13.9(11).

53

- Whether or not the implementation provides user-accessible names for the standard pool type(s). See 13.11(17).

54

- The manner of choosing a storage pool for an access type when Storage_Pool is not specified for the type. See 13.11(17).

55

- The meaning of Storage_Size. See 13.11(18).

56

- Implementation-defined aspects of storage pools. See 13.11(22).

57

- The set of restrictions allowed in a pragma Restrictions. See 13.12(7).

58

- The consequences of violating limitations on Restrictions pragmas. See 13.12(9).

59

- The representation used by the Read and Write attributes of elementary types in terms of stream elements. See 13.13.2(9).

60

- The names and characteristics of the numeric subtypes declared in the visible part of package Standard. See A.1(3).

61

- The accuracy actually achieved by the elementary functions. See A.5.1(1).

62

- The sign of a zero result from some of the operators or functions in Numerics.Generic_Elementary_Functions, when Float_Type'Signed_Zeros is True. See A.5.1(46).

63

- The value of Numerics.Discrete_Random.Max_Image_Width. See A.5.2(27).

64

- The value of Numerics.Float_Random.Max_Image_Width. See A.5.2(27).

65

- The algorithms for random number generation. See A.5.2(32).

66

- The string representation of a random number generator's state. See A.5.2(38).

67

- The minimum time interval between calls to the time-dependent Reset procedure that are guaranteed to initiate different random number sequences. See A.5.2(45).

68

- The values of the Model_Mantissa, Model_Emin, Model_Epsilon, Model, Safe_First, and Safe_Last attributes, if the Numerics Annex is not supported. See A.5.3(72).

69

- Any implementation-defined characteristics of the input-output packages. See A.7(14).

70

- The value of Buffer_Size in Storage_IO. See A.9(10).

71

- external files for standard input, standard output, and standard error See A.10(5).

72

- The accuracy of the value produced by Put. See A.10.9(36).

72.1/1

- Current size for a stream file for which positioning is not supported. See A.12.1(1.1/1).

73

- The meaning of Argument_Count, Argument, and Command_Name. See A.15(1).

74

- Implementation-defined convention names. See B.1(11).

75

- The manner of choosing link names when neither the link name nor the address of an imported or exported entity is specified. See B.1(36).

76

- The meaning of link names. See B.1(36).

77

- The effect of pragma Linker_Options. See B.1(37).

78

- The contents of the visible part of package Interfaces and its language-defined descendants. See B.2(1).

79

- Implementation-defined children of package Interfaces. The contents of the visible part of package Interfaces. See B.2(11).

79.1/1

- The definitions of types and constants in Interfaces.C. See B.3(41).

80/1

- The types Floating, Long_Floating, Binary, Long_Binary, Decimal_Element, and COBOL_Character; and the initializations of the variables Ada_To_COBOL and COBOL_To_Ada, in Interfaces.COBOL. See B.4(50).

80.1/1

- The types Fortran_Integer, Real, Double_Precision, and Character_Set in Interfaces.Fortran. See B.5(17).

81

- Support for access to machine instructions. See C.1(1).

82

- Implementation-defined aspects of access to machine operations. See C.1(9).

83

- Implementation-defined aspects of interrupts. See C.3(2).

84

- Implementation-defined aspects of preelaboration. See C.4(13).

85

- The semantics of pragma Discard_Names. See C.5(7).

86

- The result of the Task_Identification.Image attribute. See C.7.1(7).

87

- The value of Current_Task when in a protected entry or interrupt handler. See C.7.1(17).

88

- The effect of calling Current_Task from an entry body or interrupt handler. See C.7.1(19).

88.1/1

- Granularity of locking for Task_Attributes. See C.7.2(16/1).

89/1

- Limits on the number and size of task attributes, and how to configure them. See C.7.2(19).

90

- Values of all Metrics. See D(2).

91

- The declarations of Any_Priority and Priority. See D.1(11).

92

- Implementation-defined execution resources. See D.1(15).

93

- Whether, on a multiprocessor, a task that is waiting for access to a protected object keeps its processor busy. See D.2.1(3).

94

- The affect of implementation defined execution resources on task dispatching. See D.2.1(9).

95

- Implementation-defined policy_identifiers allowed in a pragma Task_Dispatching_Policy. See D.2.2(3).

96

- Implementation-defined aspects of priority inversion. See D.2.2(16).

97

- Implementation defined task dispatching. See D.2.2(18).

98

- Implementation-defined policy_identifiers allowed in a pragma Locking_Policy. See D.3(4).

99

- Default ceiling priorities. See D.3(10).

100

- The ceiling of any protected object used internally by the implementation. See D.3(16).

101

- Implementation-defined queuing policies. See D.4(1/1).

102

- On a multiprocessor, any conditions that cause the completion of an aborted construct to be delayed later than what is specified for a single processor. See D.6(3).

103

- Any operations that implicitly require heap storage allocation. See D.7(8).

104

- Implementation-defined aspects of pragma Restrictions. See D.7(20).

105

- Implementation-defined aspects of package Real_Time. See D.8(17).

106

- Implementation-defined aspects of delay_statements. See D.9(8).

107

- The upper bound on the duration of interrupt blocking caused by the implementation. See D.12(5).

108

- The means for creating and executing distributed programs. See E(5).

109

- Any events that can result in a partition becoming inaccessible. See E.1(7).

110

- The scheduling policies, treatment of priorities, and management of shared resources between partitions in certain cases. See E.1(11).

111/1

- This paragraph was deleted.

112

- Whether the execution of the remote subprogram is immediately aborted as a result of cancellation. See E.4(13).

113

- Implementation-defined aspects of the PCS. See E.5(25).

114

- Implementation-defined interfaces in the PCS. See E.5(26).

115

- The values of named numbers in the package Decimal. See F.2(7).

116

- The value of Max_Picture_Length in the package Text_IO.Editing See F.3.3(16).

117

- The value of Max_Picture_Length in the package Wide_Text_IO.Editing See F.3.4(5).

118

- The accuracy actually achieved by the complex elementary functions and by other complex arithmetic operations. See G.1(1).

119

- The sign of a zero result (or a component thereof) from any operator or function in Numerics.Generic_Complex_Types, when Real'Signed_Zeros is True. See G.1.1(53).

120

- The sign of a zero result (or a component thereof) from any operator or function in Numerics.Generic_Complex_Elementary_Functions, when Complex_Types.Real'Signed_Zeros is True. See G.1.2(45).

121

- Whether the strict mode or the relaxed mode is the default. See G.2(2).

122

- The result interval in certain cases of fixed-to-float conversion. See G.2.1(10).

123

- The result of a floating point arithmetic operation in overflow situations, when the Machine_Overflows attribute of the result type is False. See G.2.1(13).

124

- The result interval for division (or exponentiation by a negative exponent), when the floating point hardware implements division as multiplication by a reciprocal. See G.2.1(16).

125

- The definition of close result set, which determines the accuracy of certain fixed point multiplications and divisions. See G.2.3(5).

126

- Conditions on a universal_real operand of a fixed point multiplication or division for which the result shall be in the perfect result set. See G.2.3(22).

127

- The result of a fixed point arithmetic operation in overflow situations, when the Machine_Overflows attribute of the result type is False. See G.2.3(27).

128

- The result of an elementary function reference in overflow situations, when the Machine_Overflows attribute of the result type is False. See G.2.4(4).

129

- The accuracy of certain elementary functions for parameters beyond the angle threshold. See G.2.4(10).

130

- The value of the angle threshold, within which certain elementary functions, complex arithmetic operations, and complex elementary functions yield results conforming to a maximum relative error bound. See G.2.4(10).

131

- The result of a complex arithmetic operation or complex elementary function reference in overflow situations, when the Machine_Overflows attribute of the corresponding real type is False. See G.2.6(5).

132

- The accuracy of certain complex arithmetic operations and certain complex elementary functions for parameters (or components thereof) beyond the angle threshold. See G.2.6(8).

133

- Information regarding bounded errors and erroneous execution. See H.2(1).

134

- Implementation-defined aspects of pragma Inspection_Point. See H.3.2(8).

135

- Implementation-defined aspects of pragma Restrictions. See H.4(25).

136

- Any restrictions on pragma Restrictions. See H.4(27).

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