ni is a standard module, not a built-in module. The only other reference to
it already got it right.
diff --git a/Doc/lib/libni.tex b/Doc/lib/libni.tex
index 4be0d36..219f081 100644
--- a/Doc/lib/libni.tex
+++ b/Doc/lib/libni.tex
@@ -1,6 +1,6 @@
-\section{Built-in Module \sectcode{ni}}
+\section{Standard Module \sectcode{ni}}
\label{module-ni}
-\bimodindex{ni}
+\stmodindex{ni}
\strong{Warning: This module is obsolete.} As of Python 1.5a4,
package support (with different semantics for \code{__init__} and no