Glossary
Key concepts and terminology used in Metapad.
Allowed Connections
Rules in the metamodel that define which Node Types can be connected by which Relationship Types. For example: 'Application' --runs_on--> 'Server'. Without an allowed connection, you cannot draw that relationship.
Common confusion
Users often forget to set up Allowed Connections and then wonder why they can't draw relationships between nodes on the canvas.
Asset
An asset is a model element that represents a file or document attached to the model. Assets can hold files like images, PDFs, or other documents. They appear in the Assets section of the Tree View and can be placed on diagrams.
Common confusion
Assets are model elements (like nodes), not just file uploads. An asset exists in the model even without a file attached — the file is optional metadata. Removing a file from an asset does not delete the asset itself.
Diagram
A visual view of a subset of your model. A diagram shows selected nodes and their relationships on the canvas. One model can have many diagrams, each showing different aspects.
Common confusion
A diagram is NOT the model — it's a VIEW of the model. Deleting a node from a diagram does not delete it from the model. The model can contain elements not shown on any diagram.
Digital Twin
A digital representation of a real-world system, process, or organization. Metapad models serve as digital twins that can be queried, analyzed, and kept in sync with reality.
Common confusion
A digital twin is not just a static document — it's a living model that evolves with the real system.
Metamodel (M2)
The schema layer that defines WHAT TYPES of elements can exist in your model. Contains Node Types, Relationship Types, and Allowed Connections. Think of it as the 'template' or 'blueprint' for your model.
Common confusion
Users often confuse the metamodel (types/schema) with the model (instances). The metamodel defines 'Person' as a type; the model contains 'Alice' as an instance of Person.
Model (M1)
The instance layer containing actual data — specific nodes and relationships that conform to the metamodel. If the metamodel defines 'Server' as a node type, the model contains 'web-server-01' as a concrete Server instance.
Common confusion
Users sometimes try to create instances without first defining types in the metamodel.
Modeling
The practice of creating structured representations of real-world systems using nodes (entities) and relationships (connections). In Metapad, you define a schema (metamodel) and then create instances that conform to it.
Common confusion
Users sometimes confuse 'modeling' with 'drawing'. Modeling is about structured data with types and constraints, not just visual diagrams.
Node
An instance in the model (M1) that conforms to a Node Type. Each node has a label, optional description, and property values defined by its type.
Common confusion
Nodes are instances of Node Types. You must create the Node Type first before you can create Nodes of that type.
Node Type
A type definition in the metamodel (M2). Defines a category of elements with specific properties. For example, 'Server', 'Person', or 'Requirement' are node types.
Common confusion
A Node Type is the TYPE definition (like a class), not an instance. 'Server' is a Node Type; 'web-server-01' is a Node (instance).
Relationship
An instance in the model (M1) — a concrete connection between two nodes. For example, 'web-server-01 runs_on linux-host-03'.
Common confusion
You can only create relationships between nodes whose types have an Allowed Connection defined for that relationship type.
Relationship Type
A type definition in the metamodel (M2) that defines a kind of connection. For example, 'runs_on', 'manages', or 'depends_on'. Relationship types define what connections are possible.
Common confusion
Relationship Types need Allowed Connections to specify which Node Types they can connect.