Notation

The element card

Each element is drawn as a card: a rectangle with rounded corners. The shape is the same for every type; the type is recognised by its stereotype and icon, and the layer by its colour. The outline has the layer colour, and the background mixes 4 percent of the layer colour with 96 percent white.

A thin line in the layer colour divides the card in two. At the top left sits the type icon; a type without an icon shows an empty square instead. Next to the icon sits the stereotype: the technical type name split into lowercase words between « and », for example «public service». A name written entirely in capitals stays that way, for example «API». Below the line, centred and bold, sits the element name.

Layer colours

Colour belongs to the layer, not the type: all types in a layer share the same colour. Colour is for display only — an element’s layer is fixed by its type, and the layer code remains the stable identifier. On a sheet, a card’s appearance can be changed on request without changing the element’s layer. The colour of each layer is given in the table on The 12 layers page.

Relationship lines and ends

Each relationship type is drawn with a particular line and ends. The line is solid, dashed, dotted or dash-dot. The target end is an open arrow, a filled triangle or a hollow triangle; some types have none. Three types also have a source end: composition has a filled diamond next to the whole, aggregation a hollow diamond, and assignment a filled circle.

All lines share the same neutral grey; the line does not show the layer. The association line is thinner than the others. Next to the line, the editor writes the type wording in English, for example depends on. A few types have their own label: legalBasis shows § legal basis, deployedTo and hostedBy are prefixed with ⌂, and fallsBackTo shows ↺ falls back to.

Nine types share the same solid line with an open arrow: serving, deployedTo, hostedBy, legalBasis, governs, funds, measures, mitigates and affects. On a sheet, only the label tells them apart. The access relationship places its arrows by access mode: with read, the arrow sits next to the source; with write, next to the target; with no mode or readWrite, at both ends.