Support SKOS-XL

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Support of SKOSXL was discussed but JSKOS 1.0 will unlikely include it. A note about SKOSXL should be given still.

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The requirement has been come up again, so it should be supported. Add Resource type Literal with two addition fields:

• literalValue (mandatory string)
• literalLanguage (optional, can be assumed to be und by default)

Literal label fields could be prefLiteral, altLiteral, hiddenLiteral fully covering SKOS-XL.

{
  "prefLabel": { "de": "Bronze" },
  "altLabel": { "de": [ "Zinnbronze" ] },
  "prefLiteral": [ {
    "literalValue": "Bronze",
    "literalLanguage": "de",
  } ],
  "altLiteral": [ {
    "literalValue": "Zinnbronze",
    "literalLanguage": "de",
    "note": [ { "de": [ "Bronze im engeren Sinn enthalten immer Zinn." ] } ]
  } ]
}

Open question is whether and how to support note fields (scopeNote, definition, example...) as well. We could further add:

• scopeNote : scopeNoteLiteral
• definition : definitionLiteral
• example : exampleLiteral
• historyNote : historyNoteLiteral
• editorialNote : editorialNoteLiteral
• changeNote : changeNoteLiteral
• note : noteLiteral

Integrity rules

An item x with altLiteral of language y and value z SHOULD have an entry z in altLabel.y as well (and same for other literal fields prefLabel, scopeNoteLiteral...).

[nichtich]

This should also support types of labels (e.g. "name given at birth", "historic name"...)