- Clinical Guidelines are a major tool in improving the quality of medical care. However, most guidelines are in free text, not machine comprehensible, and are not easily accessible to clinicians at the point of care. We introduce a Web-based, modular, distributed architecture, the Digital Electronic Guideline Library (DeGeL), which facilitates gradual conversion of clinical guidelines from text to a formal representation in a chosen guideline ontology. The architecture supports guideline classification, semantic markup, context-sensitive search, browsing, run-time application, and retrospective quality assessment. The DeGeL hybrid meta-ontology includes elements common to all guideline ontologies, such as semantic classification, and domain knowledge. The hybrid meta-ontology also includes three guideline-content representation formats: free text, semi-structured text; and a formal representation. These formats support increasingly sophisticated computational tasks. All tools are designed to operate on all representations. We demonstrated the feasibility of the architecture and the tools for the Asbru and GEM guideline ontologies.