Converting and evolving a subject heading list into a thesaurus

Purpose The objective of this paper is to describe the evolution of the available subject heading list, i.e. the CC Soggettario (Carabinieri Corps Soggettario), towards a thesaurus, that is CCThes (Carabinieri Corps Thesaurus), to support subject indexing and retrieval of the documentary heritage held by the Historical Office of the General Command of the Carabinieri Corps. This work follows the need to implement a controlled vocabulary compliant with the state-of-the-art standards. Design/methodology/approach The methodology implements the practice of reengineering available vocabularies, following standardised guidelines for thesaurus development. The conversion process includes the balance maintenance of what has been achieved in the CC Soggettario and the enrichment of the semantic structure in the thesaurus by using both deductive and inductive methods. Findings The main result of this study is a thesaurus compliant with ISO 29964-1:2011 recommendations, which improves information retrieval performances and interoperability with other vocabularies and applications. It generally has a mono-hierarchical structure with the possibility of admitting, as an exception, the poly-hierarchy for a few concepts. An introductive user guide has been created as a complementary tool to the CCThes. Originality/value This is an applied study which deals with Knowledge Organisation System (KOS) reengineering and outlines this process using a pragmatic approach. The paper strength lies in providing the description of performed activities and conveying a set of resources to approach KOS reengineering practice. The study is also relevant for the preservation and diffusion of a part of the social memory and identity of Italy.