GSN decorators
The marks Goal Structuring Notation (GSN) lays over elements and connectors, written in one Decorators column: what to write for each, where each is drawn, the rules they are checked against, and elements with several rows.
One column for every mark
Marks from the standard are written in a Decorators column, separated by commas, semicolons or |. Element marks apply to the row's element and connector marks to the row's connection. Their names do not overlap, so one column serves both. Case, spaces, hyphens and full stops are ignored, so off-diagram and Off Diagram are the same mark.
Element marks
| Mark | Write it as | Drawn | Allowed on |
|---|---|---|---|
| Undeveloped | Undeveloped, To Be Developed, TBD | Hollow diamond beneath the element | Any element. Not together with To be supported by contract. |
| Uninstantiated | Uninstantiated, To Be Instantiated, Abstract, TBI | Hollow triangle beneath the element | Any element. |
| Undeveloped and uninstantiated | Both marks in one cell | One combined symbol beneath the element | Any element. |
| Public | Public, Publicly Visible, Exported | Small module symbol inside the top right | Goal, solution, context, assumption or justification. |
| To be supported by contract | To Be Supported By Contract, Supported By Contract, TBSBC, Contract Pending | Small module symbol beneath the element | Goals only. |
| Defeated | Defeated, Defeat, Rebutted | A cross over the whole element | Any element. |
| Off diagram below | Off Diagram, Off Diagram Below, Off Diagram Down, Continued Below, Continues Below | Filled triangle on the bottom edge | Any element. |
| Off diagram above | Off Diagram Above, Off Diagram Up, Continued Above, Continues Above | Filled triangle on the top edge | Any element. |
| Assurance claim point | ACP, Assurance Claim Point or Claim Point, followed by its identifier | Small solid square at the lower left, with the identifier beside it | Any element. |
Connector marks
| Mark | Write it as | Drawn on the connector |
|---|---|---|
| Multiplicity | Multiplicity, Multiple, Many or Cardinality, optionally followed by a cardinality such as n or 0..x | Solid ball, with the cardinality beside it |
| Optional | Optional, Optional Instantiation, May | Hollow ball |
| Choice | Choice, Alternative, One Of or M of N, optionally followed by a cardinality such as 1 of 3 | Solid diamond, with the cardinality beside it |
| Defeated relationship | Defeated Relationship, Defeated Link, Defeated Connection, Defeated Edge | A cross on the line |
| Assurance claim point on a relationship | ACP Relationship, ACP Link, ACP on Relationship or Claim Point Relationship, followed by its identifier | Solid square on the line, with the identifier beside it |
A connector carries at most one of Multiplicity, Optional and Choice. Defeated on its own marks the element; write Defeated Relationship to mark the connection.
Examples
| Decorators cell | Result |
|---|---|
| undeveloped | A hollow diamond beneath the row's element. |
| uninstantiated, public | A triangle beneath the element, and the module symbol at its top right. |
| choice 1 of 3 | A solid diamond on the row's connection, labelled 1 of 3. |
| acp ACP-7 | A square at the element's lower left, labelled ACP-7. |
| defeated relationship | A cross on the row's connection. |
An element typed Undeveloped Goal or Undeveloped Strategy carries the undeveloped mark without anything in the Decorators column.
An element with several rows
An element has one row per connection, and the Decorators cell is read on each. Write the element's own marks on one of its rows, together with any connector mark for that row's connection, and leave the cell blank on its other rows. Repeating identical text on every row also works.
When two rows of one element hold different text, the Validation tab warns A node is described by rows that disagree about Decorators; the first row's values are shown. The marks still draw: the element takes its marks from the first of its rows that has any, and each connection keeps the connector marks on its own row.
Rules and messages
| Message | Fix |
|---|---|
| The decorator column reads "mostly fine", which is not a mark this notation defines. Recognised marks are undeveloped, uninstantiated, public, defeated, off diagram and to be supported by contract on an element, and multiplicity, optional or choice on a connector. | Use one of the marks in the tables above. |
| A strategy cannot be marked as awaiting a contract. The standard applies that mark to goals only. | Remove the mark, or move it to a goal. |
| An element cannot be both undeveloped and awaiting support by contract. The standard makes the two mutually exclusive: one says nobody has argued this yet, the other says the argument is coming from another module. | Keep one of the two. While both are present, only the undeveloped mark is drawn. |
| A strategy cannot carry the public decorator. The standard allows it on a goal, solution, context, assumption or justification. | Remove the mark. |
| A connector carries multiplicity, choice at once. Each says something different about how many times the relationship is instantiated, so only one can apply. | Keep one mark on the connector. |
All of these are warnings, and the element types in the messages come from your data.