human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "policy carrying policy enforcing digital objects"
  Abstract: We describe the motivation for moving policy enforcement for access control down to the digital object level. The reasons for this include handling of item-specific behaviors, adapting to evolution of digital objects, and permitting objects to move among repositories and portable devices. We then describe our experiments that integrate the Fedora architecture for digital objects and repositories and the PoET implementation of security automata to effect such objectcentric policy enforcement.

Connected through hyperedge HE-1 (induced by source paper "the mellon fedora project digital library architecture meets xml and web services"):
  with members:
    - "flexible and extensible digital object and repository architecture fedora"

Connected through hyperedge HE-2 (induced by source paper "fedora an architecture for complex objects and their relationships"):
  with members:
    - "flexible and extensible digital object and repository architecture fedora"
    - "the mellon fedora project digital library architecture meets xml and web services"
    - "adore a modular standards based digital object repository"
    - "an information network overlay architecture for the nsdl"

Connected through hyperedge HE-3 (induced by source paper "using structural metadata to localize experience of digital content"):
  with members:
    - "flexible and extensible digital object and repository architecture fedora"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.DL(Digital Libraries)