lilypond-common-includes/default_songinfo_style.ly

\paper {
  songinfoMarkup =
    #(make-on-the-fly-markup
      (lambda (layout props m)
        (let ((between-poet-and-composer-markup (chain-assoc-get 'header:between-poet-and-composer-markup props (make-hspace-markup 3)))
              (poet-maybe-with-composer (chain-assoc-get 'songinfo:poet-maybe-with-composer props #f))
              (composer (chain-assoc-get 'songinfo:composer props #f))
              (copyright (chain-assoc-get 'songinfo:copyright props #f))
              (infotext (chain-assoc-get 'songinfo:infotext props #f))
              (translation (chain-assoc-get 'songinfo:translation props #f))
              (spelling (chain-assoc-get 'songinfo:spelling props #f))
              (year_text (chain-assoc-get 'songinfo:year_text props #f))
              (year_melody (chain-assoc-get 'songinfo:year_melody props #f)))
          (stack-lines DOWN 0.0 (chain-assoc-get 'baseline-skip props)
            (interpret-markup-list layout props
              (append
                (make-wordwrap-internal-markup-list #t (list
                  (if poet-maybe-with-composer (markup
                      (if year_text (make-concat-markup (list poet-maybe-with-composer ", " year_text)) poet-maybe-with-composer) between-poet-and-composer-markup) "")
                    (if composer (if year_melody (make-concat-markup (list composer ", " year_melody)) composer) "")))
                (make-wordwrap-string-internal-markup-list #t (string-append
                  (if copyright (string-append "© " copyright) "")
                  (if infotext (string-append "\n\n" infotext) "")
                  (if translation (string-append "\n\nÜbersetzung: " translation) "")
                  (if spelling (string-append "\n\nAussprache: " spelling) ""))))))))
      (make-null-markup)
    )
}