Here are some Requirement Levels, viewed as Keyed-Icons.
--[a --->>b ->c --]d -> O -[e --->>f ->g -]h--->
[a Survival: a lower limit on Resource use imposed by a Stakeholder SA (example corporate Policy for Quality)
>>b Fail: a minimum Tolerable-Level of Resource acceptable value to a Stakeholder SB (example a not unprofitable Level)
>c Goal: a satisfactory - successful - Level of Resource for Stakeholder SC (example: a competitive or profitable Level)
]d Survival: an upper limit on Resource use imposed by a Stakeholder SD ( example corporate Policy on single investments)
-On the System output side of things (“O->“):
[e Survival: a lower limit on a System performance Attribute, imposed by a Stakeholder SE (example Government Safety Law)
>>f Fail: a minimum Product-Value Level imposed by a Stakeholder SF ( example corporate Quality Policy or marketing)
>g Goal: a planned satisfactory value Level desired by Stakeholder SG ( example a market segment, to be competitive)
]h Survival: an upper limit on a System performance value as imposed by Stakeholder SH ( example Government determined Monopoly ..........regulation or corporate Policy about exposing ultimate capability to market and competitors too early) .
This Concept entered by Kay Dudman