====== Changes to ONIX implementation Rest 1.0 - 2.0 ======
We are making minor changes to the ONIX output of the REST interface.

  - An original title is now included, as a title composite.
  - Contributor:
    - We do not use person IDs of type "Boektrust authorship number". 
    - We are starting to use person IDs of type "VIAF". Since VIAF has not been included in codelist 44 ("Name code type") of the ONIX 2.1 standard, we use IDValue 20 and IDTypeName "VIAF".
    - Names:
      - A given person name in a Contributor composite is always the name as printed on the book. This may be the same as the author's real name, a different spelling, or an entirely different name (pseudonym). Crucial is that it is the name as printed on the book. 
      - Many contributors will also have a ''Name'' composite with ''PersonNameType'' of 04 ('Real Name'): this is the real name of the author. In the future, we will start adding authority controlled names as well, using VIAF and other identifiers. 
    - **NB** we diverge from the ONIX 2.1 standard by sending both VIAF and names. The standard says that you can //only// have a ''PersonNameIdentifier'' "without any accompanying name element(s)". We send both a ''PersonNameIdentifier'' and accompanying name elements.  
  - Illustrations: We now use fields 12.9-12.11 (''Illustrations'' composite instead of 12.7 (''NumberOfIllustrations''). This allows us to differentiate between color and b/w illustrations. 
  - Subjects: 
    - we do not use the MainSubject anymore; instead we use Subject to encode subjects. 
    - we added geocodes as subjects; these are encoded with subjectcode 23 (proprietary) with scheme name: 'BoekTrust geocode'. 
  - PublicationDate (PR 20.5) / Year First Published (PR 20.13): we now include these fields.