ISO/IEC 15026-3:2015 システムとソフトウェアエンジニアリング—システムとソフトウェアの保証—パート3：システム整合性レベル | ページ 5

3.1

adverse consequence

consequence (3.3) that results in a specified level of loss

Note 1 to entry: An adverse consequence results from the system-of-interest (3.23) being in a dangerous condition (3.4) combined with the environment of the system (3.21) being in its worst-case state (relative to the adverse consequence).

Note 2 to entry: Harm in ISO Guide 51 is an instance of an adverse consequence. The concept of adverse consequences is introduced in order to cover not only harm in the safety context but also other losses such as loss of assets in the security context.

3.2

claim

proposition representing a requirement of the system-of-interest (3.23) that enables the system-of-interest to achieve tolerable risk (3.25) if it were met

Note 1 to entry: A claim is consistent with claims in the other parts of ISO/IEC 15026 series but issues of claims here are restricted to achievement of a tolerable risk.

Note 2 to entry: A safety goal required in ISO 26262 is an instance of a claim.

3.3

consequence

outcome of an event affecting objectives

[SOURCE: ISO Guide 73:2009, 3.5.1.3]

3.4

dangerous condition

state of a system (3.21) which, in combination with some states of the environment, will result in adverse consequence (3.1)

Note 1 to entry: A hazardous situation in ISO/IEC Guide 51 and IEC 61508–4 is an instance of a dangerous condition. A concept of dangerous conditions is introduced in order to cover not only hazardous situations in the safety context but also errors in the reliability, integrity, confidentiality, or dependability contexts and other states of a system which can lead to adverse consequences.

Note 2 to entry: Occurrences of failures in the context of reliability or as defined in IEC 61508–4 often, but not always, lead to dangerous conditions.

Note 3 to entry: A dangerous condition therefore has attributes, at least, a) the associated adverse consequences, b) the trigger events that lead to the dangerous condition, and c) the trigger events that lead to the adverse consequences from the dangerous condition.

3.5

design authority

person or organization that is responsible for the design of the product

[SOURCE: ISO/IEC 15026–1]

3.6

initial risk

estimated risk (3.16) before applying risk reduction measures (3.18)

3.7

integrity level

required degree of confidence that the system-of-interest (3.23) meets the associated integrity level claim (3.10)

Note 1 to entry: The words “integrity level” forms an indivisible label. This International Standard does not pronounce on, nor depend on, a concept of integrity by itself.

Note 2 to entry: An integrity level is different from the likelihood (3.13) that the integrity level claim is met but they are closely related.

Note 3 to entry: The word “confidence” implies that the definition of integrity levels can be a subjective concept.

Note 4 to entry: In this part of ISO/IEC 15026, integrity levels are defined in terms of risk and hence, cover safety, security, financial and any other dimension of risk that is relevant to the system-of-interest.

3.8

integrity level assurance authority

independent person or organization responsible for certifying compliance with the integrity level requirements (3.11)

[SOURCE: ISO/IEC 15026–1]

3.9

integrity level definition authority

person or organization responsible for defining integrity levels (3.7) and integrity level requirements (3.11)

3.10

integrity level claim

claim (3.2) representing a requirement for a risk reduction measure (3.18) identified in the risk treatment (3.20) process of the system-of-interest (3.23)

Note 1 to entry: In general, it is described in terms of requirements that, when met, would avoid, control or mitigate the consequences (3.3) of dangerous conditions (3.4) and provide tolerable risk (3.25) .

Note 2 to entry: The claim that can be regarded as an integrity level claim in IEC 61508 is that an E/E/PE safety-related system satisfactorily performs the specified safety functions under all the stated conditions.

3.11

integrity level requirement

set of requirements that, when met, will provide a level of confidence in the associated integrity level claim (3.10) commensurate with the associated integrity level (3.7)

3.12

level of risk

magnitude of a risk (3.16) or combination of risks, expressed in terms of the combination of consequences (3.3) and their likelihood (3.13)

[SOURCE: ISO Guide 73:2009, 3.6.1.8]

3.13

likelihood

probability of something happening

3.14

property-of-interest

any property that, if lost, is considered a negative effect

Note 1 to entry: The concept of property-of-interest is introduced in order to characterize negative effects of consequences (3.3) .

Note 2 to entry: In the safety context, human lives and health are instances of properties-of-interest.

Note 3 to entry: Assets in the security context, e.g. defined in ISO/IEC 15408-1, are instances of properties-of-interest.

3.15

residual risk

risk (3.16) remaining after risk treatment (3.20)

[SOURCE: ISO Guide 73:2009, 3.8.1.6]

3.16

risk

effect of uncertainty on objectives

[SOURCE: ISO Guide 73:2009, 1.1]

Note 1 to entry: An effect is a deviation from the expected: positive and/or negative. In this International Standard, the focus is on negative deviations leading to adverse consequences (3.1) .

Note 2 to entry: Risk is often characterized by reference to potential events and consequences (3.3) , or a combination of them.

Note 3 to entry: Risk is often expressed in terms of a combination of the consequences of an event (including changes in circumstances) and the associated likelihood (3.13) of occurrence. In this International Standard, risk is characterized as the combination of the severity of the adverse consequence and the likelihood of an adverse consequence occurring.

Note 4 to entry: Objectives can have different aspects (such as financial, health and safety, and environmental goals) and can apply at different levels (such as strategic, organization-wide, project, product and process).

Note 5 to entry: Uncertainty is the state, even partial, of deficiency of information related to, understanding or knowledge of, an event, its consequence, or likelihood.

3.17

risk criteria

terms of reference against which the significance of a risk (3.16) is evaluated

[SOURCE: ISO Guide 73:2009, 3.3.1.3]

3.18

risk reduction measure

steps taken to reduce or mitigate risk (3.16)

Note 1 to entry: A typical risk reduction measure is a safety-related system in IEC 61508 series.

3.19

risk source

element that, alone or in combination, has the intrinsic potential to give rise to risk (3.16)

[SOURCE: ISO Guide 73:2009, 3.5.1.2]

Note 1 to entry: A hazard in ISO Guide 73:2009 is an instance of a risk source.

Note 2 to entry: A fault, an error, or a failure in the context of reliability can be a risk source. The definitions of those terms can be found in IEC 61508–4.

Note 3 to entry: A threat in the context of security, a threat agent (3.24) , and an adverse action defined in ISO/IEC 15408-1 can be a risk source.

3.20

risk treatment

process to eliminate risk (3.16) or reduce it to a tolerable level

[SOURCE: ISO Guide 73:2009, 3.8.1, modified]

3.21

system

combination of interacting elements organized to achieve one or more stated purposes

[SOURCE: ISO/IEC/IEEE 15288]

3.22

system element

member of a set of elements that constitutes a system (3.21)

[SOURCE: ISO/IEC/IEEE 15288]

3.23

system-of-interest

system (3.21) whose life cycle is under consideration in the context of ISO 15026

[SOURCE: ISO/IEC/IEEE 15288]

3.24

threat agent

entity that can adversely act on property-of-interest (3.14)

[SOURCE: ISO/IEC 15408‑1:2009, 3.1.71, modified]

3.25

tolerable risk

level of risk (3.12) that is accepted in a given context based on the current values of society

[SOURCE: ISO/IEC Guide 51:2014, 3.15]

Note 1 to entry: A tolerable risk is sometimes called acceptable risk, e.g. ISO/IEC/IEEE 16085, and ISO 14971. The general risk management standards ISO Guide 73 and ISO 31000 use both phrases without explicit definitions.