GSN elements and relationships
Every element and relationship type in Goal Structuring Notation (GSN), what to write for each, how each is drawn, the connections the standard permits, choices and challenges.
Core elements
| Element | Write it as | Under GSN Community Standard v3 | Under Custom |
|---|---|---|---|
| Goal | Goal, G, Claim | Rectangle | Blue rectangle |
| Strategy | Strategy, S, Argument Reasoning, Reasoning | Parallelogram | Purple parallelogram |
| Solution | Solution, Sn, Evidence | Circle | Green circle |
| Context | Context, C | Rectangle with fully rounded ends | Orange rounded rectangle |
| Assumption | Assumption, A | Oval marked A | Amber oval |
| Justification | Justification, J | Oval marked J | Grey dashed oval |
| Undeveloped goal | Undeveloped Goal, Undeveloped, To Be Developed, TBD Goal | Goal with a hollow diamond beneath | The same, in the goal's colours |
| Undeveloped strategy | Undeveloped Strategy | Strategy with a hollow diamond beneath | The same, in the strategy's colours |
| Choice | Choice, Choice Element, Structural Choice | Small solid diamond | Small dark diamond |
Modular elements
| Element | Write it as | Drawn as |
|---|---|---|
| Module | Module, Module Reference, Argument Module, M | The module symbol: a rectangle with a tab |
| Contract module | Contract, Contract Module, Contract Reference, Contract Module Reference | The module symbol with a second small rectangle |
| Module interface | Module Interface, Interface, Module Interface Connector | A small square |
| Away goal | Away Goal, Away Claim | A goal over a band naming its module |
| Away context | Away Context | A context over a band naming its module |
| Away solution | Away Solution, Away Evidence | A solution over a band naming its module |
| Away assumption | Away Assumption | An assumption over a band naming its module |
| Away justification | Away Justification | A justification over a band naming its module |
Matching ignores case, spaces, underscores, hyphens and full stops. Terms from the OMG assurance case metamodel are recognised where they correspond exactly: Claim is a goal and Argument Reasoning is a strategy. Artifact Reference is not, because it can mean evidence or context. Wording that matches nothing can be mapped under Node type values on the Data Mapping tab.
Relationship types
| Relationship type | Write it as | Joins | Under the standard | Under Custom |
|---|---|---|---|---|
| SupportedBy | SupportedBy, Supported By, Supports, Asserted Inference, Asserted Evidence | An element to what supports it. | Solid line, filled arrowhead | Dark line, filled arrowhead |
| InContextOf | InContextOf, In Context Of, Context, Asserted Context | An element to its context, assumption or justification. | Solid line, hollow arrowhead | Amber dashed line, hollow arrowhead |
| Challenges | Challenges, Challenge, Rebuts, Defeats, Counters | An element to the element it argues against. | Dashed line, hollow arrowhead | Red dashed line, hollow arrowhead |
| Module supported by | Module Supported By, Module Support, Module Dependency, Module Reference | A module to a module that supports it, in the architecture view. | Heavier line, filled arrowhead | Heavy blue line, filled arrowhead |
| Module in context of | Module In Context Of, Module Context, Module Interface | A module to a module that gives it context. | Heavier line, hollow arrowhead | Heavy amber line, hollow arrowhead |
Permitted connections
The standard lists what each relationship may join, and the visual checks against that list.
| From | SupportedBy may lead to | InContextOf may lead to |
|---|---|---|
| Goal, undeveloped goal | Goal, undeveloped goal, strategy, undeveloped strategy, solution, away goal, away solution, module, contract module, choice | Context, assumption, justification, their away forms, module, contract module |
| Strategy, undeveloped strategy | Goal, undeveloped goal, away goal, module, contract module, choice | Context, assumption, justification, their away forms, module, contract module |
| Choice | Goal, undeveloped goal, strategy, undeveloped strategy, solution, away goal, away solution, module, contract module | Context, assumption, justification and their away forms |
| Solution, away solution | Nothing | — |
A SupportedBy that starts or ends at a context, assumption or justification is reported, and so is an InContextOf that does not have exactly one of them at one end. A Challenges relationship is not checked: it may join any two elements.
Choice
A Choice element is the point where one relationship fans out into alternatives. The element above it is supported by the Choice, and the Choice is supported by each alternative. The same thing can be written as a choice mark on a connector instead; see Connector marks.
Challenges
A row with Relationship Type Challenges draws a dashed line with an open head from the challenging element to the one it argues against, and places the challenger beside its target.
To challenge a relationship rather than an element, give the relationship a Relationship ID on its row. Then give the challenging element a row with Challenged Relationship set to that ID and Connected Node ID left blank. An arrow is not drawn onto a line, so that element stands on its own, and the Validation tab notes why.