To be able to utilize the generative potential of future networks for service composition, the attributes of services and networks must be appropriately formalized, stored and made available. Important attributes are the capability and the status. A capability is an inherent property of a node or a user, which defines the ability to do something. A capability in a network node is a feature available to implement services. A capability of a user is a feature that makes the user capable of using services. Status is a measure for the situation in a system. This paper proposes a representation framework for capability and status, denoted as Unified Capability and Status Representation Framework (UniCS). This framework is used to decide upon dynamic use of capabilities, and is used to support the dynamic composition of a service system. UniCS consists of facts and configuration rules. The facts describe the availability and requirement of capabilities and status of a service system. The configuration rules verify, manipulate, transform and discover new facts with defined axioms and constraints. An instance of UniCS is the input specification for a reasoning engine to dynamically generate a composition plan for a service system.