Two terms are often used interchangeably on projects, but they come from different places and answer different questions.
LOD — level of development
LOD describes how far a model element has been developed and how much others can rely on it. It uses a numbered scale (100, 200, 300, 350, 400, 500). The best-known definitions are in the BIMForum Level of Development Specification. See LOD levels explained.
LOD is easy to communicate — one number per element per stage — which is why LOD matrices are so common.
LOIN — level of information need
LOIN starts with a purpose. For each information requirement it asks:
- Why is it needed? (purpose)
- When? (milestone)
- Who needs it? (actor)
- What is it about? (object)
It then describes the required information in three groups:
- Geometrical information — detail, dimensionality, location, appearance, parametric behaviour
- Alphanumerical information — identification and properties
- Documentation — drawings, certificates, manuals and so on
LOIN is defined in EN 17412-1, also published as ISO 7817-1, and ISO 19650 refers to it as the way to specify information requirements.
LOIN starts with why, when, who and what — then defines only the information that serves it.
In short
| LOD | LOIN | |
|---|---|---|
| Starts from | The element | The purpose |
| Expresses | A grade of development and reliability | The specific information needed |
| Covers data? | Mostly geometry and reliability | Geometry, properties and documents |
| Typical use | LOD matrix per stage | Information requirements, IDS files |
Using both
They work well together: an LOD matrix sets reliability targets per stage, while LOIN thinking keeps requests specific and avoids over-modelling. Machine-readable checks of LOIN requirements are increasingly written as IDS files.