<html><head></head><body><div style="font-family: Verdana;font-size: 12.0px;"><div>TeXbook, Appendix C: Character Codes, page 370 says:</div>
<div> </div>
<div>| (4) The \hyphenation<br/>
| and \pattern commands described in Appendix H give special interpretation to the<br/>
| ten digits and to the characters ‘.’ and ‘-’.</div>
<div> </div>
<div>I think this is a typo and instead of \pattern it should be \patterns :</div>
<div> </div>
<div>| (4) The \hyphenation<br/>
| and \patterns commands described in Appendix H give special interpretation to the<br/>
| ten digits and to the characters ‘.’ and ‘-’.</div>
<div> </div>
<div>I don't know if this has been reported earlier.</div>
<div> </div>
<div>Sincerely</div>
<div> </div>
<div>Ulrich Diez<br/>
</div></div></body></html>