A lot of other people have been working in this area since
1987!
TEI P5 must fit into a joined-up digital world, along with
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W3C standards (XLink, schema, etc)
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Unicode character encoding
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Specialized markup vocabularies (MathML, SVG, DocBook, etc)
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Other metadata schemas (METS, EAD, etc)
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Other conceptual models and ontologies
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.... and TEI P4