Chapter 3 recap
Model requirements
The key takeaways from this chapter’s 3 lessons.
LOD vs LOIN
- LOD (level of development) describes how far an element has been developed and how much others can rely on it.
- LOIN (level of information need) defines the information required for a specific purpose, at a specific milestone, for a specific actor.
- LOIN covers three kinds of information: geometry, alphanumeric data and documentation.
- Many projects use both: an LOD matrix for reliability per stage, and LOIN thinking to avoid asking for unnecessary detail.
Writing an LOD matrix your team will use
- Start from a standard element list and remove what the project does not need.
- Set targets per stage, starting at the milestone that matters most (often spatial coordination).
- Every non-empty cell needs a responsible discipline.
- List the required attributes for elements where data matters, and review the matrix at each stage gate.
Writing IDS requirements and reading the results
- An IDS specification has two halves: applicability (which objects it is about) and requirements (what those objects must have).
- Write one specification per purpose, name it in plain language and give it an identifier you can quote in issues.
- Use value rules only where the value really matters; “must be present” is often enough.
- A failing specification is a conversation starter: send the failing elements back to the author as issues or BCF, not a raw count.