chapter: The chapter heading of the source. May be wikilinked or may use chapter-url, but not both. Displays in quotes.
script-chapter: Chapter heading for languages that do not use a Latin-based script (Arabic, Chinese, Cyrillic, Greek, Hebrew, Japanese, Korean, etc); follows Romanization defined in chapter. Should be prefixed with an ISO 639-1 two-character code to help browsers properly display the script:
trans-chapter: English translation of the chapter heading, if the source cited is in a foreign language. Displays in square brackets after the chapter field; if chapter-url is defined, then trans-chapter is included in the link. Use of the language parameter is recommended.
contribution: A separately-authored part of author's book. May be wikilinked or may use contribution-url, but not both. Values of Afterword, Foreword, Introduction, or Preface will display unquoted; any other value will display in quotation marks. The author of the contribution is given in contributor.