This is one of InLOC's relationships.

equivalent to skos:closeMatch, one of the SKOS mapping properties
symmetric yes
sub-relationship exactMatch
association type LOCrel
association subject LOCstructure; LOCdefinition
association object LOCstructure; LOCdefinition; or equivalent
inheritance no
interpretation links two concepts that are sufficiently similar that they can be used interchangeably in some information retrieval applications [SKOS]