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

    record Range {
        union { null , string } start = null;
        union { null , string } end = null;
    }
    
    record ReferenceBasicMetadata {
        union { null , string } title = null;
//      author names (a single string corresponds to a single author)
        union { null , array<string> } authors = null;
        union { null , Range } pages = null;
//      the name of a journal, a book or anything that the article comes from
        union { null , string } source = null;
        union { null , string } volume = null;
        union { null , string } year = null;
        
        union { null , string } edition = null;
        union { null , string } publisher = null;
        union { null , string } location = null;
        union { null , string } series = null;
        union { null , string } issue = null;
        union { null , string } url = null;
        union { null , map<string> } externalIds = null;
    }

}