# XeLaTeX: WordInitial, Inner and WordFinal seem to match everywhere

I am creating a blackletter font and would like to use it with XeLaTeX. I try to use initial/medial/final substitution for letters, like s/ſ, but the context seems to match even when it should not.

For example, I try to execute substitution of s by ſ using the init and medi tables, but with fontspec and Contextuals={Inner}, word-initial and -final “s”es are replaced by “ſ”, too. The corresponding applies for all substitutions of initial and final forms.

\documentclass{article}
\usepackage{fontspec}
\defaultfontfeatures{Script=Latin,Language=German,Contextuals=Inner}
\setmainfont{Jena1330.otf}
\begin{document}
smstsms
\end{document}

gives a document containing ſmſtſmſ in the correct font, instead of smſtſms, as I would expect.

Am I doing something wrong? How does XeLaTeX decide if a letter is initial, medial or final?

-
 I ignored this problem now by making Jena1330 fit for vanilla pdfLaTeX, by using a manually generated pl/tfm file. (., , and so on are still considered part of the word there, though.) – Anaphory Aug 11 '12 at 0:33