@namespace("eu.dnetlib.iis.importer.schemas")
protocol IIS{

    record DataSetReference {
//      a technical ID of a data set reference (primary key)
        string id;
//      type name of the referenced id, e.g. doi
        string referenceType;
//      Data set identifier. Its definition follows the convention of a given data set
//      reference type defined by "referenceType"
        string idForGivenType;
//      Note that the ("typeID", "idForGivenType") pair unambiguously identifies a data
//      set, this is also true for the "id" field, i.e. ("typeID", "idForGivenType") is
//      a candidate key; "id" is also a candidate key.

//      additional fields
        union { null , array<string> } creatorNames = null;
        union { null , array<string> } titles = null;
        union { null , string } description = null;
        union { null , string } publisher = null;
        union { null , string } publicationYear = null;
        union { null , array<string> } formats = null;
        union { null , string } resourceTypeClass = null;
        union { null , string } resourceTypeValue = null;
    }
}