Kempf, Andreas OskarRebholz, Tobias2025-09-242025-09-242016https://repository.ifla.org/handle/20.500.14598/6212Increasing numbers of publications and decreasing personnel resources demand new methods besides intellectual subject indexing, to ensure a high quality of content-descriptive metadata even in the future. In addition, the starting situation for subject indexing has changed. A large proportion of publications already contain content-descriptive metadata from different sources. Against this backdrop, we introduce a multi-level infrastructure for subject indexing which consists of four different indexing tiers. We distinguish between intellectual indexing, semi-automatic indexing approaches, and inter-vocabulary mapping approaches for third party transfer of content-descriptive metadata from controlled as well as from uncontrolled vocabularies. Finally, we switch to retrieval and explain how the power of a controlled vocabulary for indexing can be applied for advanced retrieval scenarios.engAttribution 4.0 Internationalhttps://creativecommons.org/licenses/by/4.0/Articlehttps://2016.ifla.org/programme/satellite-meetingsopen accessSubject indexingsemi-automatic indexinginter-vocabulary mappingquery expansion