Lesson 0001 · ~12 minutes
Two halves of one system, kept apart for centuries by institutions and joined back together by a single ISO class. Learn the seam and you can place any land requirement in your data model on sight.
You are going to build a system for land. Every requirement you receive will belong to one of two families, and donor clients will use the words interchangeably even though their institutions do not. Getting the seam right on day one is the difference between a model that survives contact with a real registry and one that has to be rewritten.
Historically these were literally different buildings with different professions: surveyors ran the cadastre, lawyers and notaries ran the register. Many countries still have two agencies, two databases, and one very unhappy integration layer.
The compressed version, as the standards literature puts it: cadastre concerns mostly spatial information, whereas the land registry deals generally with the legal.1 Neither half is useful alone. A cadastre without a register is a map of parcels nobody owns; a register without a cadastre is a list of rights over land nobody can find.
LADM — the Land Administration Domain Model, ISO 19152 — exists to describe both halves in one formal language. Its stated purpose is not to replace national systems but to let their similarities and differences be understood.1 That is exactly what you need when a donor project spans three countries with three legal traditions.
Edition I was the single document ISO 19152:2012. Edition II is multi-part — Part 1 overview, Part 2 land registration, Part 3 marine, Part 4 valuation, Part 5 spatial plan. EN ISO 19152-1:2024. Say "LADM Part 1" in a proposal and you sound current; say "ISO 19152:2012" and you sound like 2015.
The whole model rests on four core classes:2
| Class | Holds | Half |
|---|---|---|
LA_Party | People and organisations that hold or transact rights | Legal |
LA_RRR | Rights, Restrictions, Responsibilities — abstract, with those three subclasses | Legal |
LA_BAUnit | The administrative unit a homogeneous set of rights applies to | The seam |
LA_SpatialUnit | Parcels, buildings, networks — geometry, or a point, or even text | Spatial |
LA_Party — LA_RRR — LA_BAUnit — LA_SpatialUnit is a sentence: somebody holds some kind of claim over an administrative unit that is located somewhere. The BAUnit is the seam. It is why one ownership can cover three adjoining parcels without duplicating the right three times, and why a parcel can be resurveyed without touching the rights over it.
Two things this buys you immediately. First, LA_RRR being abstract over right, restriction and responsibility means a mortgage, an easement, and a maintenance obligation are siblings, not special cases bolted onto ownership. Second, LA_SpatialUnit permits a point or a text description, not just a surveyed polygon — which is what makes fit-for-purpose approaches representable in a standards-conformant model at all.
FAO's SOLA Suite is the reference implementation worth reading: an open-source land administration system whose "underlying data structures are based on the Land Administration Domain Model." Note how the split shows up in its component list — SOLA Registry covers rights registration and cadastre together, while Systematic Registration is a separate component because bulk first-registration is a different workflow, not a different data model. Stack: PostgreSQL/PostGIS, GeoServer, Payara, JasperReports.3
Classify each item. Some are deliberately awkward; that is where the learning is.
Read van Oosterom's ISO/TC 211 LADM workshop deck — the model's co-author walking through the core classes with the actual diagrams, free, no standards paywall:
Oosterom — LADM Workshop, Quebec (PDF)
Look specifically at the class diagram and check it against the sentence you learned above. If the diagram surprises you anywhere, that surprise is the next lesson.