本文以國家圖書館第一階段CMARC3與CMARC4欄位225、327、856格式功能與轉換系統開發作業為主，試論相關編目規範、格式轉換工具及系統功能的配合，並比較CMARC3與CMARC4優缺點，探討格式轉換的影響與衝擊，分析系統開發所遭遇的困難與限制，期望以切身經驗，供他館參考或借鏡。

This article focuses on the first stage of the NCL's CMARC III to CMARC IV conversion system development, including Tag 225 and Tag 327 of the CMARC III, and Tag 856 of the CMARC IV. It discusses the coordination of cataloging rules and regulations, CMARC format conversion tools, and relative library system functions. Furthermore, it compares the advantages and disadvantages of CMARC III with CMARC IV, probes into the influence and impact on CMARC format conversion, and analyses difficulties and limitations of developing the CMARC format conversion system. In the end, we hope other libraries can benefit from our experiences.