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

// At least one of rawText, destinationDocumentId, externalDestinationDocumentIds fields is not empty.
    record CitationEntry {
//      position of citation in the bibliography of the source document
        int position;
//      raw citation text
        union { null , string } rawText = null;
//      cited document OA+ identifier (if referenced document is present in OA+)
        union { null , string }  destinationDocumentId = null;
//      A number from [0, 1] range. The greater the value, the greater the
//      confidence that the document->document citation link is correct.
//      The `confidenceLevel` field is null if and only if the `destinationDocumentId` is null.
//		Find more details on `confidenceLevel` constraints in eu/dnetlib/iis/README.markdown file.
        union { null , float } confidenceLevel = null;
//      cited document identifiers (id type -> id)
//      WARNING: Id types are extracted from PMC data without any processing thus are subject to change without notice.
//               Currently (2014-05-12), the most popular types are "pmid" (PubMed ID) and "doi".
        map<string> externalDestinationDocumentIds;
    }
}