Core Concepts Overview
This section explains the conceptual foundations of Fractal OSI modeling. You do not need to read these pages before building your first model — but returning to them after the Quick Start will deepen your understanding of why the editor works the way it does.
The Five Conceptual Areas
1. The FML Type System
The Fractal Modeling Language is an 8-class taxonomy that gives you a universal vocabulary for any domain. It defines what kinds of things can exist in a model and what kinds of relationships can connect them.
2. Entity, Role, and Act
The three Base Classes are the building blocks of every Fractal OSI model. Understanding the distinctions between them — especially the Entity/Role distinction — is the single most important conceptual leap in Fractal OSI.
3. The Four Associative Classes
Relationships in Fractal OSI are first-class typed objects, not visual connectors. The four Associative Classes — Participation, ActRelationship, RoleLink, and ScopeLink — each carry distinct semantic meaning about how things connect.
Read: The Four Associative Classes →
4. FractalSets: Models Within Models
A FractalSet is a saved canvas placed inside another canvas. It can be designated as an Entity, Role, or Act — making it a full participant in the type system. FractalSets are the mechanism for recursive composition.
5. FractalParent: Inline Grouping
A FractalParent is a grouping boundary drawn directly on the canvas to contain and visually organize a set of nodes. Unlike a FractalSet, it does not become a separate canvas and does not participate in the type system.
Reading Order
If you are new to Fractal OSI, read these pages in order:
- The FML Type System — understand the full 8-class vocabulary
- Entity, Role, and Act — understand the Base Classes
- The Four Associative Classes — understand how things connect
- FractalSets — understand recursive composition
- FractalParent — understand inline grouping
If you are an experienced modeler coming from UML, ER, or BPMN, start with Entity, Role, and Act for the key distinctions, then read The Four Associative Classes for the semantic relationship model.