There is no <ISINPUT> element, just <ISINDEX>. ;-)
diff --git a/Doc/lib/libcgi.tex b/Doc/lib/libcgi.tex
index b24d490..e4a8e21 100644
--- a/Doc/lib/libcgi.tex
+++ b/Doc/lib/libcgi.tex
@@ -22,7 +22,7 @@
\nodename{cgi-intro}
A CGI script is invoked by an HTTP server, usually to process user
-input submitted through an HTML \code{<FORM>} or \code{<ISINPUT>} element.
+input submitted through an HTML \code{<FORM>} or \code{<ISINDEX>} element.
Most often, CGI scripts live in the server's special \file{cgi-bin}
directory. The HTTP server places all sorts of information about the