Metadata is an essential tool for electronic records management and preservation; it has received high attention in maintaining the authenticity,integrity,usability of electronic records and enabling the understanding of information objects. Among the related metadata standards and guidelines,metadata models,which play the role of ‘meta-standards’,can provide a basic framework for both the authorities and the organizations to develop concrete schemes. The most widely used metadata models in records and archives management field include recordkeeping metadata conceptual model of ISO 23081,preservation metadata model of PREMIS and technical environment information model of PRONOM. But none of them initially serves the purpose of the long-term preservation of electronic records,no matter which metadata model is applied in records preservation organizations,some kind of refinement,expansion or adjustment is always needed.

    This paper aims at building a unified metadata model for electronic records preservation through analyzing,comparing and integrating the metadata models of ISO 23081,PREMIS and PRONOM. As an inclusive solution of the existing standards,this unified model provides a common conceptual framework for electronic records preservers to formulate metadata application profile and support metadata reuse between electronic records preservation system and electronic records management system.The construction of unified metadata model starts from the actual demands of electronic records preservation by the way of modular design. By comparison the authors find that the records entity,people (agents) entity,business entity and mandates entity of ISO 23081 metadata model can be successively mapped to the object entity,agent entity,event entity and rights statement entity of PREMIS metadata model; furthermore,the records entity and the object entity can complement each other,so do the business entity and the event entity of these two models. The metadata model of PROMOM enriches the description of the technical environment of electronic records,which has great significance to digital information representation. Compared with PREMIS and PRONOM,ISO 23081 can better support the professional principles including the sustainable management of electronic records and their metadata throughout the records life circle,multi-level description of records and the integration of records and business. Therefore the authors lay the basis of architecture and terminology of the unified metadata model more on ISO 23081 while taking the advantages of the other two. The model is comprised of five entities including records entity,technological environment entity,agent entity,business entity and mandate entity. The records entity has multiple levels including archives collection,fond,series,file and item in managerial dimension,whereas in technical dimension the levels cover representation,computer file and bit stream. The technological environment entity refers to the systems and technologies used in creating,managing,preserving and rendering electronic records. The agent entity refers to the individuals,organizations or automated equipment taking part in creating,managing and utilizing electronic records. The business entity refers to the business of creating,managing and preserving electronic records. The mandates entity refers to the rules that normalize business execution and records access. The relationships between entities are set as attributes of the entities rather than an independent entity.〖JP.

    The unified metadata model for electronic records preservation constructed in this paper,in comparison to ISO 23081,enriches the content of records entity by integrating records preservation business with records creation business and recordkeeping business,and promotes the ability to meet long-term preservation requirements by adding a new technological environment entity. Compared with PREMIS,it turns the object entity into records entity and event entity into business entity,which better reflects the characteristic of records management; moreover,it makes the technological environment an independent entity from object entity. As for PRONOM,the technical components entity can be mapped to the technological environment entity of the unified metadata model,whereas the identifiers entity,intellectual property rights entity,documentation entity and actors entity can be mapped to the attributes of the technological environment entity of the unified metadata model. Some of the findings in this paper need further practical verification. 8 figs. 29 refs.