This page shows how different Schemes implement the string-titlecase procedure when the character to be titlecased has a multi-character titlecase mapping. The string-titlecase routine may come from SRFI-13, from R6RS, or may be a Scheme extension. The example used is ﬂoo, which begins with a fl ligature character.
The Unicodely correct way of titlecasing this string is to treat the ligature the same as fl, in which case the result is Floo. However, by the strict letter of R6RS, the ﬂ character is passed to char-titlecase, which in this case will return its argument unchanged. What is more, if the ﬂ character is not even seen as a letter, then the result will be ﬂOo.
Result is Floo: Racket, Chicken (with the utf8 egg), Larceny
Result is ﬂoo: Scheme48/scsh, Guile, Kawa, SCM, Ypsilon, Mosh, STklos, Dfsch, Sagittarius
Result is ﬂOo: Gauche, plain Chicken, Chez, Vicare, Sizzle
No string-titlecase procedure that I could find: MIT, Gambit, Bigloo, JScheme, KSi, Sigscheme, Shoe MiniScheme, TinyScheme, Scheme 9, S7, XLisp, Rep, Schemik, UMB, Elk, Llava, SXi, FemtoLisp, LMU, Inlab, Foment, Picrin, Owl Lisp, Chibi
Failure of some other kind: IronScheme, NexJ, RScheme, Unlikely, SIOD, BD