The RT Topology Library exposes an API to create and manage standard
(ISO 13249 aka SQL/MM) topologies using user-provided [data stores]
(doc/DATASTORES.md) and released under the GNU GPL license
(version 2 or later).

The code is derived from PostGIS liblwgeom library enhanced to provide
thread-safety, have less dependencies and be independent from PostGIS
release cycles.

The RT Topology Library was funded by “Regione Toscana - SITA”
(CIG: 6445512CC1), which also funded many improvements in the
originating liblwgeom.