Class

Value

Symbol

High

Partial unavailability, if unrepairable.
Total unavailability, if long-term.
H

Medium

Partial unavailability, if repairable (short-term or long-term).
Total unavailability, if short-term.
M

Low

Noticeable degradation, repairable (short-term or long-term) or unrepairable.
L

Extremely high

Very long-term or unrepairable unavailability of the service.
V

Extremely low

Unnoticeable effects, or no actors affected.
U

Ambiguous

Indicates lack of consensus between analysts.
A

Unknown

Indicates lack of knowledge or data.
X

Not yet analysed

Default. Indicates that no assessment has been done yet.
-