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    | • | 
    Multiple
    contexts, views, application
    & user 
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    perspectives 
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    Multiple
    levels of precision, specification, 
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    definiteness
    required 
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    Multiple
    levels of semantic model 
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    verisimilitude, fidelity, granularity 
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    | • | 
    Multiple
    kinds of semantic mappings, 
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    transformations
    needed: 
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    – | 
    Entities,
    Relations, Properties, Ontologies, Model 
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    Modules,
    Namespaces, Meta-Levels, Facets (i.e., 
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    properties of
    properties), Units of Measure, 
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    Conversions, etc. 
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