This web site presents a thesaurus for the domain of cadastre and land administration. The domain regards the surveying and mapping of land, including the boundaries of land parcels, as performed by the profession of surveyors. From a public point of view, the domain provides the technical base for taxation of land and buildings, and for land use planning; from a private point of view, the domain supports security in ownership and other land-related rights.

The term Cadastre is related to Venetian (1185) catastico ("list of citizens possessing a taxable property"), which through 18th century French developments was adopted into English meaning 1. a public survey of land for the purpose of taxation, and 2. a register of such surveys, showing details of ownership and value. The term Land Administration appears in a 1973 Seminar on Land Administration in Kuala Lumpur, Malaysia [1]. The UN/ECE in 1996 published Land Administration Guidelines with special reference to countries in transition, and authors of a textbook on Land Information Management in 1999 issued a renewed version with the title Land Administration [2].

Scientific reflection of this domain resulted in 2002 in a proposal for the development of a standardized Cadastral Core Domain Model based on the geographic standards from ISO and OpenGIS (from 2004: Open Geospatial Consortium, OGC) and to be developed in cooperation with the International Federation of Surveyors, FIG [3, 4]. The proposal was through further developments finally approved as the ISO 19152:2012 Land Administration Domain Model (LADM). The draft LADM standard made the base for preparation of the initial version of CaLAThe, which was related also to existing thesauri, primarily the GEMET thesaurus, the  AGROVOC thesaurus, and the STW Thesaurus for Economics, and issued September 2011. Version 3 was supplemented with terms from the OGC Land and Infrastructure Conceptual Model Standard (LandInfra), and the present version 4 includes code lists from both standards.

The Cadastre and Land Administration Thesaurus, in short CaLAThe, is encoded as a Simple Knowledge Organization System (SKOS), according to specifications developed by the World Wide Web Consortium (W3C). As of December 2019, CaLAThe is hosted at the OGC Definitions Server.

The user can in addition access the thesaurus here through term search as well as an alphabetical listing, and through graphical overviews, which render the main groups: Activity, Information, Land, Law, Party, and Survey, respectively, in addition to graphical rendering of all thesaurus term relations. Finally, the development of CaLAThe is outlined in Version overviews.