Roles

A role states what an element is. A design system sets how each role looks. The core gives every object and connection exactly one role, as the first entry of its D2 class list.

db: Orders {class: store}              # you pick the role
api: Orders API {class: [node; data]}  # role, then a design-system class

An element without a role gets its diagram’s default role (marked * below). D2 applies classes in order, and later classes take precedence. Classes you add after the role override the role’s styling.

Modifiers

Modifiers work in every diagram type. inkline does not treat them as roles.

The carbon design system adds the architecture modifier prescribed and these domain colours: security, devops, application, data, network, observability, vpc, compute and backend.

Roles by diagram

architecture

flowchart

sequence

A group, which is a top-level container that holds messages, takes no role.

state

class

Write connections from the child, implementer, whole or dependent end.

er

block

swimlanes

quadrant

treeview

inkline assigns roles by depth. The top level is root, a node with children is a branch and every other node is a leaf.