to match text which spans lines; this does not work reliably. While
@code{font-lock-fontify-buffer} handles multi-line patterns correctly,
updating when you edit the buffer does not, since it considers text one
-line at a time.
+line at a time. If you have patterns that typically only span one
+line but can occasionally span two or three, such as
+@samp{<title>...</title>}, you can ask font-lock to be more careful by
+setting @code{font-lock-multiline} to @code{t}. But it still will not
+work in all cases.
@node Other Font Lock Variables
@subsection Other Font Lock Variables
@code{font-lock-keywords} as well as adding them to this list.
@end defvar
+@defvar font-lock-syntactic-face-function
+A function to determine which face to use for a given syntactic
+element (a string or a comment). The function is called with one
+argument, the parse state at point returned by
+@code{parse-partial-sexp}, and should return a face. The default
+value returns @code{font-lock-comment-face} for comments and
+@code{font-lock-string-face} for strings.
+
+This can be used to highlighting different kinds of strings or
+comments differently. It is also sometimes abused together with
+@code{font-lock-syntactic-keywords} to highlight elements that span
+multiple lines, but this is too obscure to document in this manual.
+@end defvar
+
@node Levels of Font Lock
@subsection Levels of Font Lock