The document discusses the Global Forest Domain Classification (GFDC) and its implementation in the Global Forest Information Service (GFIS). It notes that classifications are important for organizing information as they allow for "browsing" and creating ontologies and topic maps. GFDC is a hierarchical, multilingual classification for forest and forestry information that is maintained by IUFRO. The document recommends using GFDC for subject metadata in GFIS and developing browse and search interfaces based on GFDC categories. It also provides technical requirements and possibilities for implementing GFDC in GFIS such as using RSS/RDF formats and the Open Archives Initiative Protocol.