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Knowledge organization systems denotes formally represented knowledge that is used within the context of digital libraries to improve data sharing and information retrieval. To increase their use, and to reuse them when possible, it is vital to manage them adequately and to provide them in a standard interchange format. Simple knowledge organization systems (SKOS) seem to be the most promising representation for the type of knowledge models used in digital libraries, but there is a lack of tools that are able to properly manage it. This work presents a tool that fills this gap, facilitating their use in different environments and using SKOS as an interchange format.
Unlike the largely unstructured information available on the Web, information in digital libraries (DLs) is explicitly organized, described, and managed. In order to facilitate discovery and access, DL systems summarize the content of their data resources into small descriptions/ usually called metadata/ which can be either introduced manually or automatically generated (index terms automatically extracted from a collection of documents). Most DLs use structured metadata in accordance with recognized standards, such as MARC21 (U.S. Library of Congress 2004) or Dublin Core (ISO 2003).
In order to provide accurate metadata without terminological dispersion, metadata creators use different forms of controlled vocabularies to fill the content of typical keyword sections. This increase of homogeneity in the descriptions is intended to improve the results provided by search systems. To facilitate the retrieval process, the same vocabularies used to create the descriptions are usually used to simplify the construction of user queries.
As there are many different schemas for modeling controlled vocabularies, the term knowledge organization systems (KOS) is intended to encompass all types of schemas for organizing information and promoting knowledge management. As Hodge (2000) says, "A KOS serves as a bridge between the users' information need and the material in the collection/7 Some types of KOS can be highlighted. Examples of simple types are glossaries/ which are only a list of terms (usually with definitions), and authority files that control variant versions of key information (such as geographic or personal names). More complex are subject headings/ classification schemes/ and categorization schemes (also known as taxonomies) that provide a limited hierarchical structure. At a more complex level, KOS includes thesauri...