Due to the dynamic and complex characteristics of knowledge organization systems (KOS), the need for a multi-layered model to present the complex relationships among KOS resources is widely recognized. This paper reports on a continuous effort to establish such a model. Prior to this paper, a general Dublin Core Application Profile (DCAP) model was proposed using the FRBR (Functional Requirements for Bibliographic Records) conceptual model as the foundation. The current study applies the general DCAP model to KOS. It introduces a domain model that is suitable for describing and accessing KOS resources and incorporates the core attributes that the NKOS (Networked Knowledge Organization Systems) group has surveyed and summarized. The domain model includes the entities, relationships between entities, and the core attributes of the entities in the context of user tasks. The results reflect access-related properties that are complementary to the previous research by NKOS group members that focused on description-related metadata properties commonly found in KOS registries.