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Internal Representation

When records are manipulated by the system, they're represented in a tree-structure, with data elements at the leaf nodes, and tags or variant components at the non-leaf nodes. The root-node identifies the schema that lends context to the tagging and structuring of the record. Imagine a simple record, consisting of a 'title' element and an 'author' element:


     ROOT 
        TITLE     "Zen and the Art of Motorcycle Maintenance"
        AUTHOR    "Robert Pirsig"
    

A slightly more complex record would have the author element consist of two elements, a surname and a first name:


     ROOT  
        TITLE  "Zen and the Art of Motorcycle Maintenance"
        AUTHOR
           FIRST-NAME "Robert"
           SURNAME    "Pirsig"
    

The root of the record will refer to the record schema that describes the structuring of this particular record. The schema defines the element tags (TITLE, FIRST-NAME, etc.) that may occur in the record, as well as the structuring (SURNAME should appear below AUTHOR, etc.). In addition, the schema establishes element set names that are used by the client to request a subset of the elements of a given record. The schema may also establish rules for converting the record to a different schema, by stating, for each element, a mapping to a different tag path.