In fact, though Chapter 12 still exists in the TOC of the document, the relevant chapter (Statistical Models in R) has mysteriously become chapter 11 (it was a long time ago that I last looked at it). The relevant section is ?11.1 Defining statistical models; formulae.
http://cran.r-project.org/doc/manuals/R-intro.html
Regards, Mark.
Mark Difford
Ph.D. candidate, Botany Department,
Nelson Mandela Metropolitan University,
Port Elizabeth, SA.
This look like a generic texinfo issue affecting HTML output. Numbered
sections are off by one when the first section (here Preface) is
unnumbered. Same thing in R-exts.html and others.
(CC to Kurt Hornik because he usually knows texinfo things.)