Core Concepts
Specifications
Understanding how IDS specifications work
A Specification defines a validation rule for IFC models. Each specification contains applicability criteria and requirements that elements must meet.
Structure of a Specification
Each specification has three main parts:
1. Description
Explain why this requirement exists. Good descriptions help model authors understand the purpose of the specification.
2. Applicability
Identifies which elements in the model this specification applies to. Use facets to filter:
- Entity Facet - by IFC class type
- Property Facet - by property values
- Classification Facet - by classification references
- Material Facet - by material assignments
- Attribute Facet - by IFC attribute values
3. Requirements
Defines what information the applicable elements must have. Use the same facet types to specify required data.
Cardinality
Specifications can be set as:
| Type | Meaning |
|---|---|
| Required | Matching elements must exist in the model |
| Optional | If matching elements exist, they must meet requirements |
| Prohibited | Matching elements must not exist in the model |
Using IDSedit
In the visual editor:
- Create a specification node
- Connect applicability facets to the left
- Connect requirement facets to the right
- Configure each facet's parameters
- Set the cardinality as needed
Learn More
For complete specification details, see the official IDS documentation.